The New Advent page provides the Greek, Latin and Knox English in a parallel text version. You can listen to the Latin here and the Greek here. Here is the Latin:
19 Cum ergo sero esset die illo, una sabbatorum, et fores essent clausæ, ubi erant discipuli congregati propter metum Judæorum: venit Jesus, et stetit in medio, et dixit eis: Pax vobis. 20 Et cum hoc dixisset, ostendit eis manus et latus. Gavisi sunt ergo discipuli, viso Domino. 21 Dixit ergo eis iterum: Pax vobis. Sicut misit me Pater, et ego mitto vos. 22 Hæc cum dixisset, insufflavit, et dixit eis: Accipite Spiritum Sanctum: 23 quorum remiseritis peccata, remittuntur eis: et quorum retinueritis, retenta sunt. 24 Thomas autem unus ex duodecim, qui dicitur Didymus, non erat cum eis quando venit Jesus. 25 Dixerunt ergo ei alii discipuli: Vidimus Dominum. Ille autem dixit eis: Nisi videro in manibus ejus fixuram clavorum, et mittam digitum meum in locum clavorum, et mittam manum meam in latus ejus, non credam. 26 Et post dies octo, iterum erant discipuli ejus intus, et Thomas cum eis. Venit Jesus januis clausis, et stetit in medio, et dixit: Pax vobis. 27 Deinde dicit Thomæ: Infer digitum tuum huc, et vide manus meas, et affer manum tuam, et mitte in latus meum: et noli esse incredulus, sed fidelis. 28 Respondit Thomas, et dixit ei: Dominus meus et Deus meus. 29 Dixit ei Jesus: Quia vidisti me, Thoma, credidisti: beati qui non viderunt, et crediderunt.30 Multa quidem et alia signa fecit Jesus in conspectu discipulorum suorum, quæ non sunt scripta in libro hoc. 31 Hæc autem scripta sunt ut credatis, quia Jesus est Christus Filius Dei: et ut credentes, vitam habeatis in nomine ejus.
 Now when it was late that same day, the first of the week, and the doors were shut, where the disciples were gathered together, for fear of the Jews, Jesus came and stood in the midst, and said to them: Peace be to you.  And when he had said this, he shewed them his hands and his side. The disciples therefore were glad, when they saw the Lord. He said therefore to them again: Peace be to you. As the Father hath sent me, I also send you.  When he had said this, he breathed on them; and he said to them: Receive ye the Holy Ghost.  Whose sins you shall forgive, they are forgiven them; and whose sins you shall retain, they are retained.  Now Thomas, one of the twelve, who is called Didymus, was not with them when Jesus came.  The other disciples therefore said to him: We have seen the Lord. But he said to them: Except I shall see in his hands the print of the nails, and put my finger into the place of the nails, and put my hand into his side, I will not believe. And after eight days again his disciples were within, and Thomas with them. Jesus cometh, the doors being shut, and stood in the midst, and said: Peace be to you.  Then he saith to Thomas: Put in thy finger hither, and see my hands; and bring hither thy hand, and put it into my side; and be not faithless, but believing.  Thomas answered, and said to him: My Lord, and my God.  Jesus saith to him: Because thou hast seen me, Thomas, thou hast believed: blessed are they that have not seen, and have believed.  Many other signs also did Jesus in the sight of his disciples, which are not written in this book. But these are written, that you may believe that Jesus is the Christ, the Son of God: and that believing, you may have life in his name.
The Catena Aurea's commentaries highlight the weakness of the apostles:
CHRYS. The disciples, when they heard what Mary told them, were obliged either to disbelieve, or, if they believed, to grieve that He did not count them worthy to have the sight of Him. He did not let them however pass a whole day in such reflections, but in the midst of their longing trembling desires to see Him, presented Himself to them: Then the same day at evening, being the first day of the week, when the doors were shut where the disciples were assembled for fear of the Jews.
BEDE. Wherein is strewn the infirmity of the Apostles. They assembled with doors shut, through that same fear of the Jews, which had before scattered them: Came Jesus, and stood in the midst. He came in the evening, because they would be the most afraid at that time...
CHRYS. It is wonderful that they did not think him a phantom. But Mary had provided against this, by the faith she had wrought in them. And He Himself too showed Himself so openly, and strengthened their wavering minds by His voice: And says to them, Peace be to you, i.e. Be not disturbed. Wherein too He reminds them; of what He had said before His crucifixion; My peace I give to you; and again, In Me you shall have peace.
GREG. And because their faith wavered even with the material body before them, He showed them His hands and side: And when He had said this, He showed them His hands and His side.
The significance of his breathing on them:
CHRYS. Having then given them confidence by His own miracles, and appealing to Him who sent Him, He uses a prayer to the Father, but of His own authority gives them power: And when He had said this, He breathed on them, and says to them, Receive you the Holy Ghost.
AUG. That corporeal breath was not the substance of the Holy Ghost, but to show, by meet symbol, that the Holy Ghost proceeded not only from the Father, but the Son. For who would be so mad as to say, that it was one Spirit which He gave by breathing, and another which He sent after His ascension?
GREG. But why is He first given too the disciples on earth, and afterwards sent from heaven? Because there are two commandments of love, to love God, and to love our neighbor. The spirit to love our neighbor is given on earth, the spirit to love God is given from heaven. As then love is one, and there are two commandments; so the Spirit is one, and there are two gifts of the Spirit. And the first is given by our Lord while yet upon earth, the second from heaven, because by the love of our neighbor we learn how to arrive at the love of God.
CHRYS. Some say that by breathing He did not give them the Spirit, but made them meet to receive the Spirit. For if Daniel's senses were so overpowered by the sight of the Angel, how would they have been overwhelmed in receiving that unutterable gift, if He had not first prepared them for it! It would not be wrong however to say that they received then the gift of a certain spiritual power, not to raise the dead and do miracles, but to remit sins: Whosoever sins you remit, they are remitted to them, and whosoever sins you retain, they are retained.
AUG. The love of the Church, which is shed abroad in our hearts by the Holy Spirit, remits the sins of those who partake of it; but retains the sins of those who do not. Where then He has said, Receive you the Holy Ghost, He instantly makes mention of the remission and retaining of sins.
GREG. We must understand that those who first received the Holy Ghost, for innocence of life in themselves, and preaching to a few others, received it openly after the resurrection, that they might profit not a few only, but many. The disciples who were called to such works of humility, to what a height of glory are they led! Lo, not only have they salvation for themselves, but are admitted to the powers of the supreme Judgment-seat; so that, in the place of God, they retain some men's sins, and remit others. Their place in the Church, the Bishops now hold; who receive the authority to bind, when they are admitted to the ram; of government. Great the honor, but heavy the burden of the place. It is ill if one who knows not how to govern his own life, shall be judge of another's.
On Thomas' doubts:
ALCUIN. Didymus, double or doubtful, because he doubted in believing: Thomas, depth, because with most sure faith he penetrated into the depth of our Lord's divinity.
GREG. It was not an accident that that particular disciple was not present. The Divine mercy ordained that a doubting disciple should, by feeling in his Master the wounds of the flesh heal in us the wounds of unbelief. The unbelief of Thomas is more profitable to our faith, than the belief of the other disciples; for, the touch by which he is brought to believe, confirming our minds in belief, beyond all question.
CHRYS. As to believe directly, and any how, is the mark of too easy a mind, so is too much inquiring of a gross one: and this is Thomas's fault. For when the Apostle said, We have seen the Lord, he did not believe, not because he discredited them, but from an idea of the impossibility of the thing itself: The other disciples therefore said to him, We have seen the Lord. But he said to them, Except I shall see in His hands the print of the nails, and put my finger into the print of the nails, and thrust my hand into His side, I will not believe. Being the grossest of all, he required the evidence of the grossest sense, viz. the touch, and would not even believe his eyes: for he does not say only, Except I shall see, but adds, and put my finger into the print of the nails, and thrust my hand into His side.
AUG. He might, had He pleased, have wiped all spot and trace of wound from His glorified body; but He had reasons for retaining them. He showed them to Thomas, who would not believe except he saw and touched, and He will show them to His enemies, not to say, as He did to Thomas, Because you have seen, you have believed, but to convict them: Behold the Man whom you crucified, see the wounds which you inflicted, recognize the side which you pierced, that it was by you, and for you, that it was opened, and yet you cannot enter there.
GREG. Our Lord gave that flesh to be touched which He had introduced through shut doors: wherein two wonderful, and, according to human reason, contradictory things appear, viz. that after the resurrection He had a body incorruptible, and yet palpable. For that which is palpable must be corruptible, and that which is incorruptible must be impalpable. But He showed Himself incorruptible and yet palpable, to prove that His body after His resurrection was the same in nature as before, but different in glory.
AUG. Thomas saw and touched the man, and confessed the. God whom he neither saw nor touched. By means of the one he believed the other undoubtingly: Thomas answered and said to Him, My Lord and My God.
THEOPHYL. He who had been before unbelieving, after touching the body showed himself the best divine; for he asserted the twofold nature and one Person of Christ; by saying, My Lord, the human nature by saying, My God, the divine, and by joining them both, confessed that one and the same Person was Lord and God.