Boyfriend can’t commit

I’m 12+1, so my boyfriend and I don’t have the best relationship we have trust issues when it comes one other we have been together for 3 year. So this morning I just happened to find in his phone that his friend and him were planning to have sex with these girls but one backed out, so they were just going to have sex with one of them. And he tells all his friends that we aren’t in a relationship and I’m just his bm he wants to live two different lives like I’m nothing to him when comes home to me every day and sleeps with me every night, but I live with him. I told him if he keeps doing this I would leave him because I’m tired of him doing this to me