My answer is quite different with the question, did Jesus really say those words?
Well, this question critically involves the issue of the historicity of Jesus, which is an distinct but important matter. However it is not accurate to base a criticism of the place of this logion in early Christian tradition solely on the legitimacy of the gospel of John, since the saying is not confined to John but is also well attested in varying forms across different literary traditions: (1) the Synoptic tradition in Mark 14:58, 15:29, Matthew 27:40, Acts 6:14, (2) the Johannine tradition in the text under consideration, and (3) the Thomasian tradition in Thomas 71:1. The text is also interpreted in a range of ways (whether referring to the literal Temple or Jesus' body) and applied to various narrative contexts....suggesting that this was an accessible piece of tradition adapted in different ways by late first century and early second century writers.
The gospel of John was not heard of till about the year 180 A.D., about a hundred years after John's death and it wasn't untill the close of the second century the book was even attributed to him, and then by the fathers of the church.
I disagree. Even if there were no attestation of the book before AD 180, this does not mean that the gospel was "not heard of" until then. This is making a positive claim on negative evidence, and our knowledge of the period is incomplete. For example, Papias explicitly mentions the writings of "Matthew" and "Mark", and no comment exists for John, but does this mean that he did not know John or does it mean that by chance his comment did not survive? In fact, only a scant amount of material from Papias' five-volume work survives. So it is rather better to say that there is "no evidence" of the book before AD 180.
But even this is probably not true for earlier attestations and allusions do exist. (1) Rylands 457 (P 52 ) is generally accepted as dating to the first half of the second century, earlier than c. AD 180; (2) 1 John is clearly familiar with John and alludes especially to the Prologue and the Farewell Discourses. The date of 1 John is clearly earlier than that of Polycarp's letter to the Philippians (which attests 1 John 3:8 and 4:2-3 in Polycarp 7:1), which itself must have been written before Polycarp's martyrdom in c. AD 155-160, and probably dates to c. AD 110-140; (3) 2 Peter 1:13-14 represents Jesus as having predicted Peter's death, and this is probably an allusion to John 21. The date of 2 Peter is unclear, but probably between AD 100-150; (4) Justin Martyr (c. 156 AD) also likely alludes to John; the logion in 1 Apology 61.4 is a version of John 3:3-5 (tho it could have also come from free tradition); (5) Justin's student Tatian was certainly familiar with the text of John, as he included it in the Diatessaron in c. AD 172; (6) Heracleon, a Valentinian gnostic, wrote a commentary on John roughly between AD 150 and 180 (cf. the excerpts preserved by Origen and Clement of Alexandria's remarks on Heracleon); (7) Irenaeus (c. AD 180-185) was the first to explicitly mention John's gospel and its presumed authorship (Adversus Haereses 3.11), but he indicated that it was used for quite some time earlier by mentioning its use in his sources. He cites the logion in John 14:2 and its interpretation by the presbuteroi (likely the presbyters known to Papias) in Adversus Haereses 5.36.1-2. He also cites a Valentinian commentary on the Prologue of John in Adversus Haereses 1.8.56 (written by Valentinius' disciple Ptolemy), indicating the use of the gospel in this school in the mid-second century.
As you correctly note, the gospels originally circulated anonymously and their traditional ascriptions are of secondary origin.
Some scholars determine the work to be a forgery and the apostlic fathers such as Clement of Rome (97A.D.)never mention Matthew, Mark, Luke, or John.
I think "forgery" is not the right word here; such a word might better be applied to pseudepigraphic works, and even then it should be qualified. As for the lack of gospel allusions in 1 Clement, this is not because Clement of Rome found the works offensive or non-authoritative but rather because he wrote too early to have been acquainted with them. The same is true with most other NT books and apostolic fathers, who instead cite and allude to logia in the free tradition. It is not until you come to the anonymous homily of 2 Clement and Justin Martyr that we see use of gospel harmonies or Papias (c. AD 140-150) on the presumed authors of the gospels.
Finally a christian Father Papias, who lived around 150 A.D. does mention a Gospel according to Mark. Of him Eusebius said that Papias was a man of limited comprehension and the tradition that he collected of Jesus were rather too fabulous.
He also mentions a composition by Matthew. Papias is important because he gives a window into early Christian storytelling and oral tradition, which helps shed light on how the gospel traditions developed.
In 150 A.D. Justin Martyr made 314 quotes from the Old Testament where in two-thirds of the cases he mentions the book he was quoting, yet when making his so-called New Testament quotations, he never once mentioned the 4 gospels as we know them and yet he mentions the Gospel of Peter and the Acts of Pilate.
It is interesting, isn't it? It is possible that what he calls the Memoirs of Peter is Mark (cf. Papias on the authorship of Mark), but it is unclear what he meant by the Acti Pilati. Most, or nearly all, of his gospel harmonizations are derived from Matthew and Luke, suggesting that these are the gospels he was most familiar with. He does cite some agrapha from the free tradition, such as the saying in Dialogue 47.5.
The first writer to mention John's gospel is Theophilius of Antioch in 180 A.D. and says nothing of him being an apostle.
Not true, see above. The Valentinian commentary cited by Irenaeus, for instance, does attribute John 1:1 (the same passage cited by Theophilus of Antioch) to "John, disciple of the Lord":
Further they teach that John the disciple of the Lord disclosed the first octet, and their exact words are as follows: "John the disciple of the Lord intentionally spoke of the origination of the entirety, by which the parent emitted all things. And he assumes that the first being engendered by God is a kind of 'beginning'; he has also called it 'son' and 'only-begotten god'. 'In this' (the only-begotten) 'the Father' emitted 'all things' in a process involving seeds. By this Son, he says, was emitted the Word, in which was the entire essence of the aeons that the Word later personally formed. Now since he is speaking of the first origination, he does well to begin the teaching at the beginning, with the Son and the Word. He speaks as follows: 'The Word was in the beginning, and the Word was with God. And the Word was God. It was in the beginning, with God.' First, he distinguishes three things: God, beginning, and Word. Then he unites them: this is to show forth both the emanation of the latter two, that is, the Son and the Word, and their union with one another and simultaneously with the Father. For the beginning was in the Father and from the Father; and the Word was in the beginning and from the beginning" (Valentinian Ptolemy, cited in Irenaeus, Adversus Haereses 1.8.5).
According to Layton, the Valentinian Ptolemy (who lived in Rome and spread the Valentinian school in Italy) must have written sometime after AD 136-40 and before Irenaeus quoted him in AD 180, and if he is the same Ptolemy that was martyred in Rome in AD 152, then his book would have been written before then.
The first mention of all four gospels is by Irenaeus about 200 A.D.
A bit closer to AD 185, according to most authorities.