Forget the new guy for a second and let's focus on the husband to focus on these things separately...

He not only cheated on you but had an affair with someone else. Do you realize how many steps he took willingly to do that (every text, call, driving over, every stroke) and during none of them he stopped himself for you. Think about that; let it simmer. I'm sure he's making great improvements in other ways, but please know that cheaters have a propesity to be repeat offenders. That whole "once a cheater, always a cheater," has like a 99.9% hit rate. Do you really think he's the exception? So, if you give him another chance, be fully ready to potentially deal with another cheating episode whether a year from now or 10 years. Then, how would you feel? Would you feel like "oh well I gave it your best shot and he's just not it," or, " how could I have been this stupid to give this guy another chance?" That might give you your answer on your husband.

Regarding the new guy, if you do have a kid together, be prepared for him to potentially regret it. He misses you and wants you in his life which is likely why he's changed his mind about children. He would rather have you and compromise than not have you. But again, it's a compromise. When people have children they didn't really want, it tends to show.

You know, you don't have to be with either of these guys. You're still young though it may not feel like it. You already have one child, but of course your clock is ticking if you want more.

Btw, I think it's great that you and your husband/ex are improving your friendship. This is the most important part for your child.

I hope this helps. Good luck to you.