There are an awful lot of red flags about this man in your opening post. His "behaviour", his stubbornness, his having "gone quiet" (what does this mean, exactly?) on you before (more than once?).
I'm very sorry but I do not think this is going to resolve in the way you want it to. Why should you be worried that you will never forgive this, surely abandoning a heavily pregnant women is exactly the sort of behaviour that shouldn't be forgiven! (I assume that by "forgive" you mean forget about it and pretend it never happened, of course you should try to forgive in the sense of not holding a grudge forever as that's not good for you.)
A man (or woman) who is this "stubborn" and uncaring will not make a good parent. Is he punishing you? Nothing about it sounds functional.
I would lean heavily on your other sources of support. Begin imagining the birth and parenting without him. Who will be your birth partner now? Also consider what you will do if he reappears before the birth - I appreciate you've said the relationship is over for you now so I would not allow him to be at the birth, the role of the birth partner is to be a support and advocate for YOU and not some sort of spectator. You won't need him in there (or even outside) with all of this emotional baggage. Not being present at the birth does not prevent him from being a good parent should he so choose.
I would stop trying to contact him now. Presumably he knows how to contact you. Send him a short message once the baby has arrived ("Healthy baby boy born at 6:17pm on Thursday 25th August") and get in a claim for child maintenance immediately. Don't give the child his surname. I wouldn't be keen for him to have any unsupervised contact with the child if he does come crawling out of the woodwork, either he's having a massive mental health crisis or he is a complete twat (or both).
Be aware that you cannot name the father on the birth certificate if he is not present for the registration appointment if you are not married. On the plus side, not being on the birth certificate would mean he wouldn't have parental responsibility for the child. He can apply to court to be added later if he wants. You can claim maintenance from him even if he's not on the birth certificate.
I'm very sorry that he's turned out to be like this. I hope your baby brings you lots of joy and that one day all of this stress and sadness will be a distant memory. You can do this.