(I wrote half a message yesterday, then came back later to finish it, but when I went to post it my account had timed out and so it all lost it! Sorry for the delayed response)
Thats a good question @Tootsy .
For a few years I had been trying to remove stress from my partner, hoping that it would give him some reprieve to feel better in mood and then his behaviours improve also. But they didnt, no matter how much I took off his plate - and that included any social burden of having to chat to me or support my mental health.
Over the past year I deliberately sought out more social and support opportunities with friends, because I knew I could not ask/expect them from my partner anymore.
In short- I progressively made myself more and more independent and not expecting/needing anything from him (physically, emotionally, financially). Which then put me in a position to be able to say "something needs to change" and know that he may choose to leave but that I can cope with that.
I found talking to a trusted friend really helpful because I could tell them all the ways I have tried over the past few years to improve things, all the ways I have encouraged my partner to seek help/support for his brewing mental illness... and that at the end of this nothing changed with him. And how when I said something needs to change, this wont last longterm, his response was that he didnt know if he wanted to try - and thus moved out whilst he figures that out.
My friend was able to validate to me that I have made a big effort and bent over backwards (way more than she would of 😅) and put up with a lot, but that yes the best thing for me is to speak up for my needs and say something needs to change. And if he chose to end the relationship instead of address the issues, then that is *not* my fault. I did everything I could to try and make it work.
In your case, given the high risk of DV, I agree with @tyme about being concerned for your safety.
Are you able to move elsewhere?
I know there are often a lot of barriers to this for people - be it financial, childcare, concerns for retaliatory aggression, physical dependence...
Can I ask what your barriers are (if any) to moving out - even if it is temporary until he can control his own behaviours/threats! - to ensure your safety and mental wellbeing?