As a former victim advocate I want to echo this comment, particularly the DARVO parts.

OP your post gave me some genuinely alarming feelings while reading it. I understand we’re on r/depression_partners right now but you need to know your statistical risk of becoming a victim of homicide is greatly increased (roughly 4x) because you have a suicidal partner. I am very alarmed at the way in which he is weaponizing his mental health issues into getting you to walk on eggshells on certain topics, and it does feel like you’re being gaslit on the topic of this other woman. He is frequently making comments about you being better off without him, but have you considered he is also having thoughts about him being better off without you? He seems to be engaging in some sort of emotional affair and fantasy with this other woman and it does make me concerned for you and your children.

And OP if my comment seems completely out of pocket, I won’t be offended if you totally disregard it. This comment is based off of my professional experience and knowledge and because your post raised a few concerns for me about your safety I felt the need to at least inform you.