In hindsight, while I was fighting with the AH about whether or not he had a problem, I wish I'd held him accountable for the threats he made. The suicide attempts, ideations, and threats, especially. You can't be the thought police and you can't modify your life to save her. If it ever goes past idle comments, I'd call her on it.
Or, you know, you could decide whether or not this relationship is the hill you want to die on.
I also want to say, as someone who has battled some deep, dark depression, that it was wise for you to stop sexual contact with your partner after that. Especially with women, the conflation of sex, death, and self-destruction is definitely a part of poor mental health. Not sexy. Red flag.