I am so impressed with you. You have 100% done the right thing for you and for your DC. You will get stronger, and happier, and any doubts or guilt you have will subside until they disappear completely.
You shouldn't feel any sort of guilt. Remind yourself that this man has abused you, controlled you and your DC, made you all walk on eggshells, thought only of himself and what makes him happy. Even when he was being nice it was just part of his game to manipulate and control you. He doesn't have yours, or your DC's best interests at heart, only his own.
Anything he says, anything he does, from hereon, is aimed at getting what he wants, which is the easiest life and no loss of image. He may lie, gaslight, sulk, flatter, make promises, wild promises, love-bomb, admit fault (then change his mind again) - anything it takes to get you back in his control.
But you've seen through him, and you will never un-see it. You deserve so much better than him. You will be happy as a capable, happy single mum, with your lovely DC. You can do what you like, go where you like, eat what you like, relax in your own home. Your DC will benefit hugely. I'm so happy for you all.
Keep strong, and if you waiver, keep reading your own and other posts on here, and keep posting, and remember that he may mess with your head but you know the truth - he is abusive, you can't trust anything he says, you're better off without him and so are your DC.