Please help

I don’t know where to post this so please forgive me.

I’ve been in a relationship for 7 months now. We are also engaged. From day one I’ve always known his been a bit weird but never to this extreme.

Every night we do the same thing. Kinda getting boring you know and I try to tell him but he switches.

He has 3 personalities in him. One is very strangely a “dark lord”. He thinks he can do some magic etc and thinks this “demon” is powerful and controls him sometimes. I forgot to mention we also live together so I can’t get away from this when he acts like this.

He can now see he needs help, but can’t control it. He drink excessive alcohol and has also switched on me personally. I love the boy and want to help him but need advice because he can’t help but turn to alcohol..😓