How can I help someone who has become spiritual to the point it seems like delusion/mental illness

My boyfriend and I have always shared an interest in the new age spiritual such as astrology, eastern medicine, new age practices. He has gone so far down the deep end to me it's completely delusional and has been going on for almost a month. He believes he is a super healer and almost like a deity, sees astral beings, believes he can heal the world with his mind, can control weather, and so on While some of this could be possible in my spiritual beliefs to an extent - I don't think it is possible to happen so intensely and all at okce happening in his case and it seems more like mental illness/skiztophrenia He says he wants no professional help as he's never been better and has come into his highest purpose I try to call him out on what I believe to be delusions but he's ten toes down in what feels real for him.

I've been wanting to break up with him before all this but have been waiting for the right time and this relationship has become extremely draining for me. Lost for what to do him as he wants no help. He deeply does not want to be put in an institution so to an extent I have to respect that and maybe leave that up to his family as I can't keep going on like this

Any and all advice greatly appreciated please