Love triangle...

In General, there is a very good man, my friend. He has a wife. And I'm sleeping with his wife. And so I ugly that at heart, I feel like a scoundrel. Well, I mean, while I'm with her I'm in seventh heaven. So happy I have never been in my life. But when she leaves, in my head begin to climb thinking that I was doing everything wrong. Not to ruin someone else's family. Moreover, she already has a child. But to stop seeing her I don't want to. How to be? I'm at a complete loss.