Hi.
Based on what you wrote about your ex, there isn't much that can be deciphered. Some generalizations perhaps but to be fair to the guy, such generalizations or conclusions should not be made.
However, since you do seem concerned, especially since the guy did father your child and also since your child will eventually ask about his father, there are some things we can reasonably deduce.
Honestly, I think he's a bit guilty and totally lost. He stuck out on a limb just by being your boyfriend with this whole Montague-Capulet situation your families supposedly have. There are just some people who cannot handle the repercussions of their actions and this SEEMS to be such a case. Guilt also seems to be part of all this as seeing you is causing him pain. Truth hurts and seeing you forces him to come face to face with 1) having gone against his family, 2) fathering a child out of wedlock, 3) forcing abortion on you and not winning, 4) having to go to his mom for help about the abortion and still not winning, 5) having left you in a flat that he spent for, 6) knowing that people in school that he was a bit of a jerk (okay, maybe a big bit) and 7) maybe the kids in your school are getting on his case for not having the guts to do this or that. It's possibly a whole lot of things and really, somewhere along the way, the two of you have to talk.
You can initiate it if you want or you can opt to just figure all the days of your life that he's a jerk. Some people do that a lot but then again, maybe you can't do that just for the sake of your son. Don't be fooled when people tell you that you can forget about him and that you can raise your child alone. Yes, you can raise him alone but you owe it to your son to give him the truth about his father and sadly, for the sake of your son also, you have to make sure that your son's meeting his father will be as painless for him as possible -- regardless of how you feel about the dad.
Why do guys do these things? Because they're kids and there are many things kids aren't that prepared to handle yet even if they think they are. That's why parents throw a fit when their kids get involved in pregnancies. I'm sorry your folks threw you out but when you're 35 and your son tells you he got someone pregnant, a girl from a family you really despise, well, you get the idea.
Please take care and hang tight for your son. You have a long road ahead of you.
Erick