I think he probably feels a mixture of guilt and relief, but the main thing is you’re getting out of this situation - so well done OP.
I was on the previous thread under another username but I’ve just seen all your updates now and so glad to hear you’ve been able to make it out before Christmas!
He may not be completely horrible, most people aren’t but he’s definitely not cut out to be a stepparent or anything like that. Tbf IMO most people aren’t and they don’t do it that well, which is why I’m glad my single parent mum didn’t ever move a man in.
Your ex has just been especially awful about it and revealed his inability to treat your daughter kindly in a very obvious manner.
I do agree he has been masking and it’s scary that he was able to switch back so easily to being all jovial and friendly with your daughter once he realised you were rethinking things.
It makes you wonder how genuine is he in general and do you really know him at all?
He started showing his true self with your daughter but it could very easily have been you next. And based on his cruelty to your daughter and the silent treatment to both of you and his weird lie about the driving, he was well on his way to revealing himself as a a full blown manipulative and moody abuser.
Even the minimisation of the driving license lie is quite gaslighty. He is pretending as if it’s not a massive deal when he knows it is. Not that he doesn’t drive, but that he would lie about it. He’s messing with your head.
So yeah don’t feel bad at all when he is being nice or helpful about your love. It’s good he is being like that but at the same time it’s the very least he could do really.