Finding Strength

My husband has cheated on me during our entire relationship and is in love with this girl and was in love with her before me. I have always known this and have forced him to stay and be with me even though I know he loves someone else. He was forced into marrying me and it has been a disaster but I was desperate because I couldn´t find love and now I am too scared to be alone but I am in a dead marriage that never really existed. How can I find the strength to leave and find someone who will love me?