Op nothing wrong with what you're feeling at all imo.
My ex treated dd and I like shit after we split. I could understand him treating me like shit, even though it was him to blame for the split but treating dd like shit is absolutely unacceptable!
I learned a couple of years ago that he and wife 2 (OW and former supposed friend) are utterly fucking miserable! They're married and have 5 DC 1st dc was conceived when we were still very much together.
He's cheating on her repeatedly (inc at one point with the best friend she'd had since nursery which destroyed that friendship, he also propositioned me the night before their wedding which at the time I brushed off as cold feet panic nonsense) she feels trapped and is staying because she has seen how he behaved as a nrp to dd (not seeing her, not even speaking to her for several years, not paying cm in any reliable way) and fears he would do the same to their kids and she couldn't afford to be a single parent if he wasn't paying cm. I've heard she is staying until the youngest hits high school age and no longer needs childcare and then she's off.
I've seen photos and they both look completely knackered and miserable. His skin is playing up awfully (which is an external/visible indicator of stress for him) and she looks older than me despite being over 10 years younger.
Am I secretly pleased their actions have led to them both being completely fucking miserable? Hell yes! The only people I have any compassion/empathy for in the whole mess are the kids involved.
I can't imagine it's a very happy household especially as ex when stressed is a snappy, irritable, cruel, bad tempered git!!