Hey Nicole!
I am sorry that you have to go through all this. If I were in your situation, I would think about the events which led to the break up. You need to reanalyze them from a third point of view, like you are in a movie watching yourself and your fiance. See things from his perspective. Why did he act that way? why is he being nice now?
To be honest, his controlling behavior is a red flag and sooner or later its gonna become a major problem for you since you hate that. No one should tolerate it as far as that is concerned. These traits are often found in narcissistic and manipulative men. Do confront him about this. He may be acting nice now and become his usual self once he gets you back.
I know you want to do it for the children but the truth is, even if you guys do get back together, they will grow up in a dysfunctional household which is far more painful than being brought up by a single parent. You can set an example for them as well by being strong in these bad times, standing up for yourself and respecting your boundaries.
Good luck! Hopefully you’ll make the right decision 🙂