I really do believe people have a whole story behind why they feel a certain way. Hsppyfarm tells us one snippet and it doesn't convey the years of issues, even subtle events and gestures that feed the current reaction.
The biggest issue is the fact her husband is not standing up to behaviour, probably much more over the years, and that's really hard to deal with.
With the place I am at right now realising so much, I couldn't be in space with anyone for long perpetuating that which I'm fighting to claw out of.
@Happyfarm because it's so difficult watching your husband in this dynamic, I'd probably cut contact myself with the family even more, doing only Christmas or one other huge event and that's it. Don't do any cards and expect nothing back. You're not stopping husband from doing his thing, but you're disconnecting from them.
Leave it entirely to him and tend to yourself a bit more. If you can sort out things for yourself and childcare, I'd be making that your priority.
It feels like you have no escape mentally and physically from difficult people you're exposed to.