I'm married to a woman in love with a man
That sounds very complicated. Why did you marry someone who was in love with another man?
I married her because of my love for her
It must be unfortunate to be married to someone like that. You should either seek marriage counseling or get a divorce.
I love my wife and she loves me
It's wonderful that you two love each other, but it isn't healthy in the long run for her to be in love with someone else too. Don't you want her full attention? Why not try talking to her, so you can try to save your marriage?