Seen this from all sides.
Grew up with two parents arguing to the point where I became a ward of court.
Took up responsibility for my ex’s little girl from the age of 3 (and much like your situation), she’s now 17 and a really smart kid.
Now left my ex and my own 2 girls 400miles away, but she refuses to let them stay with me for holidays etc.
In Scotland unless you’re married you have very few rights to the kids,but I’d never stop providing for them. So women can equally be as difficult.
Just grin and bare it, but never speak out of turn about their Dad in front of them.