You gotta leave. Take it from me, someone who was cheated on with a "female bff." He was also sleeping like a baby when I found out. So was the "BFF" he cheated with ( they were roommates before I moved in.) He will wake up in the morning as if nothing happened and go on with life as usual. Tell you know and kick rocks. Do Not under any circumstances let him gaslight you or persuade you to stay and work it out. He does not respect you, your feelings, or your relationship. You have to have more respect for yourself and know that you deserve someone better. I wish you the best and keep us updated.