I think am in love with my best friend's husband

I am in love with my best friend's husband. He is a wonderful husband and father of 2. I can't say he came after me because I went after him. It started as a joke, then I thought a one-time booty call wouldn't hurt. But it turned out he is a tiger in bed, and I can't stay away from him. I know he can't leave his wife, he loves her, but I know he loves me too. He does a lot for me and also can't stay away from me. I once suggested that he marries me too but he said that if I can convince his wife to accept polygamy, he will do it as it is acceptable in both their cultures. But my friend hates polygamy; I have asked her many times, all she says is that, if her husband would want to marry another woman, she would leave him. But my agony is that, I love this man to an extent of turning down other men.