Most Helpful Guy
Here's what I see:
You got together with this guy at a very young age, and got very emotionally attached (extremely common with first real relationships). When it started to go wrong, though, you didn't have the confidence to break up with him and move on. You kept going back and back and back. For a certain percentage of people, they do this: they don't end a relationship that is LONG dead because they still have feelings, and because they're afraid to lose that history they had together, so they stay in an unhealthy relationship much longer than they should have. That's you.
As you've said, this new guy is everything you really wanted. Except he's not what you are used to, and he's not your first love. You're trying to hold on to that first love, as SO MANY girls do. It's just that most girls lose their first love in Jr High or High School, spend 6 months crying over it, and then realize that life isn't over, and they learn to move on. You've never really learned to move on.
Your ex is now back and trying to pull you back in. Yes, maybe he's done some work, but the truth is that if you go back with him, in 6-12 months, things will be just like they always were. All of his "changes" will revert because, like you, he's been in this same relationship for too long. Meanwhile, you will have SH!T all over the new, good guy, because you have committed to him and then essentially cheated on him with your ex.
The chances of you having a healthy, life-long relationship with your ex is very, very low at this point. I won't say impossible, but VERY improbable. I believe that if you pursue this with your ex, that in 2-3 years, you'll be alone in NY, facing a divorce and who-knows-what other problems (financial? baby? legal?), and wondering how things could have gone so wrong.
I recommend you make a clean break from your ex and focus on your current guy, and if you can't do that, then be honest with him and break up with him. What you are doing right now isn't fair to him at all.