I'm sorry you're going through such a rough time.

Do you think it might help if you expressed your feelings? To her or, to avoid or manipulation, to a journal? It sounds like you have a lot of hurts you haven't been able to discuss because you're stuck in her issues.

Have you tried using positive affirmations to replace those brooding thoughts? That helps me a lot if I can remember to do them!

It's good that you're starting to recognize your trigger points. I think that will help you to deal with this better and better in the future.