I think that she married a very rich older man, knowing full well what he was like, and had fully expected that she wouldn't actually see very much of him, given his business schedule, and that she would be able to lead a relatively quiet and pampered life and bring up her son in their gigantic apartment in Trump Tower before her grim husband either died or she was able to divorce him.
I'm 100% certain that she had no idea he was going to a) run for President some day or b) win, and I think she is horrified that this happened. He has completely destroyed any chance that she (or their young son) can ever have of just leading a standard rich family's life and I think she hates Trump for it. I think she's massively embarrassed by him, is fully aware that he is borderline insane, that she is very miserable. It's pretty telling, I think, that she isn't going to move into the White House with him and is staying in New York with Barron.
Whether he is actually abusive, as such, is something only she can know and I don't think any of us can really make assumptions about that, but I think we can safely say that it's not a happy marriage for her. She looks as she completely despises him half the time and his body language around her is so dismissive, as if she was an accessory rather than a human being.
However, he has always been a total bellend, so it's not like she wouldn't have known what he was like when she married him. There is no way it's a case of someone marrying a charmer and only later discovering what a complete shit he was. Trump has always been Trump.
I dread to think what their prenup was like.