Relationship problems

So...my bf wanted a poly relationship i'm not ready or comfortable for one we were doing good on our own Just the Two of Us but when I refused he got angry and went to go tell the third person (lets call them 'M') i don't know this person at all and he's known them for years it was just really awkward after telling M that I wasn't comfortable for the poly relationship they tried to overdose of course that got me & my bf really worried we didn't want anybody to get hurt afterwards my bf refuse to talk to me for the day, next day he scolded me for not paying attention and telling me how I knew that M was sensitive I don't know anything about this person like I said I don't even know them now my bf chooses to ignore me and leave me on read idk what too do.