People can change.

It might be useful to discuss the past issues w/ him to see how he reacts & if he seems genuinely repentant about hurting you. Be frank that you’re not sure if you can get past what happened. If he is faking it this discussion might be revealing if he responds in a negative manner. If he isn’t faking change & is really different he will be completely OK w/ it & genuinely sorry.

Give it awhile. A good while. 2 weeks isn’t very long to see if it is real change. It is OK to let your self get in the moment of the new improved him, but keep some protective distance that time will tell if this is real genuine change.

The bigger issue is likely to be if you want to get back. He may have really changed, but you may not want to ultimately get back. This would likely mean that you would be 2 exes that were OK w/ each other & thats a decent situation for the child. You can love some things about him, but this not be enough. While you are having any doubts about this it isn’t nearly time yet for the 2 of you to move back in.

I just checked the date of your former post. It was only on 8/16/11 that you posted that you just found out that he cheated over 20 times. This isn’t very long at all. This is only 2 1/2 weeks since you found out. A few weeks isn’t nearly enough time to see if he reverts into his former behavior of cheating. Are you just taking his word that he isn't still cheating? He may still be in repair damage mode. Time will tell if this is a real change.

Given that it was only 2 1/2 weeks ago that you found out, I would modify the suggestion to talk to him about it. This may be appropriate in a few months, but right now he is probably being too aware of having to say the right things to see if this is real. Let him get out of repair damage mode & settling back into regular life to gauge the relationship. Is what caused him to cheat going to resurface after he gets out of damage control mode?