I had a ton of guilt, too.
To make matters worse, my AH got diagnosed with Type 1 diabetes while we were married.
I knew that wouldn't change my support of him. Why should alcoholism?
But the piece I was missing was that I mattered.
A story that relates is a friend of mine (L) had a friend (C) that was diagnosed with cancer. C turned demanding and snappish. C would breeze through town, expect L to drop everything and take care of her, and C would drop off her cats, even if it was inconvenient - expecting L to take care of them, too.
My friend, L, started to feel VERY taken advantage of. But she felt horribly guilty at setting boundaries around someone so needy.
Finally, she realized she was getting treated like dirt.
And, ultimately, it didn't matter if C was the queen or dying of cancer or just a jerk. C was acting like a jerk and L didn't deserve it.
L was kind, but set boundaries with C about how she was willing to be treated (and how she wasn't!).
Same story with you. It doesn't matter why she is being a jerk sometimes. She has choices to heal.
YOUR job is to take care of YOU. What is and is not acceptable? What boundaries can you set so you are treated right?
You can love her and support her healing AND set boundaries while you do so.
p