I have a very similar situation myself, tolerating a toxic family member in order to have access to a family member I love and respect.

I second Soupe's recommendation about coping mechanisms. I would take some time to try and build that up. It'll suck not seeing your godsons for a while, but it would be worth it to build the resilience to handle whatever slings of misfortune she flings your way.

One recommendation I have would be to find ways to have some control, some agency in your interactions with her. Stuff like staying in a hotel if she tries to get you to stay with her. Or having a set time to leave her house. If there's a family get-together that you could meet everybody at rather than at their place, that might be good. Whatever can act as a pressure valve for your anxiety and frustrations and/or give you a way to get out of there if she starts affecting your mental health like she has.

The other thing I do is detach. Ever played Civilization? It's a computer game where you take a nation or empire from the beginning of history to the Space Age and beyond. As befitting such a game, you have a diplomacy screen where you can make treaties, demand or give tribute and more. The point I'm getting to is is sometimes the only way for me to stay on an even keel is to treat this family member (my dad) not as family but as a particularly aggressive city-state that you're sitting at the negotiating table with. In some small way, it makes his posturing seem less personal.