I need help

My marriage is failing. My (48m) wife (35f) and I are close to splitting up. She has OCD and PMDD. She recently switched SSRI meds, and she is not herself. During hell week(s), she usually singles out one person to hate. Sometimes it's her dad, mom, brother, the neighbor, or me. When it's me I just keep my head down and wait for it to pass. For the past few months, even before the med switch, her pmdd and ocd has gotten really bad. She's thinks I'm saying things that aren't true. She becomes an emotional wreck and I'm left to be the emotional punching bag. For her past few cycles, her pmdd changes when she gets her period. So instead of the pmdd going away, she gets extremely angry until ovulation. So she has a few days out of the month where she is herself.

Some more context, she is trying to quit taking THC, which she is addicted to. She is taking sedatives at night. She says I'm not being supportive because I told her that she can do it, but if not, then that's okay because she is trying to take on a lot right now.

Every month, our fights get worse and worse. And today, we agreed to split. I didn't want to, but she was egging it on. She kept throwing my ADHD around like that's our major malfunction. Yes, ADHD has caused some bad decisions on my part. But at least my diagnosis doesn't threaten to end our 15 year marriage every month with crying fits.

What do I do? How do I save this? I want my old wife back before the PMDD.