Okay so recently I have been feeling naive trying to get back with my ex and he gave me an ultimatum that I just don't think I can do.. he told me one thing I can do to get him back is to fulfill his fantasy which is a reverse gang bang. He wants me and him to "have fun" with multiple women. I feel a relationship is between a man and a women and no other outsiders I consider it cheating.. he believes it's just a little fun and that adults do it regardless. I don't want to and I have very high standards and morals. Should I just let him go. Because I don't think I'll ever be able to fulfill his fantasies, & I don't think he'll ever respect the fact that I don't want to...

What do I do, any thoughts on the topic.