My man told me he wants me to limit contact with my cousin

My cousin is very mentally ill... he is legit the sort of person who a manipulative person might successfully convince to do bad things. He’s not all there... and he is impressionable.

Recently he became a satanist (man whatever) and my boyfriend told me that he wanted me to limit contact because he doesn’t like the way I feel responsible for him or the way he relies on me or the way he’s just so unstable as not to want him around. But the satanism was the last straw I think; he is trying to commune with demons and frankly I’m not here for it. He doesn’t know what the fuck he’s doing. But he lives in a reality apart from my own and I can’t always reach him with reason.

Personally I don’t like it either... I wouldn’t be too comfortable alone with my cousin if he was having a psychotic break... But he is isolated and disturbed and I feel like I can’t just abandon him.

I made it clear (to my cousin since he asked about us being room mates) that I wouldn’t be his caregiver in the future and that being room mates wouldn’t work out bc it just doesn’t like up w my plans (a family). So I feel like I’ve set boundaries. SO doesn’t seem satisfied though and says some people you shouldn’t be in too much contact with.

Opinions?

It’s not a non-negotiable in our relationship or anything but if it was, I don’t know what I would do. My boyfriend would never suggest something he didn’t think was best for me. I count him as family too, in a very serious way because he is something to me that no one else is. He’s my high school sweetheart so he’s always looked out for me and I trust him to have the best intentions... He’s my very best friend.

We’re all adults late 20s.