Mixed feelings

I cut my ex off my social life, she kept going on about how she didnt need for us to be friends, but how she still liked being friends with me. She cheated on my with this guy she used to have a crush on, and I forgave her for that, and moved on, trying to be a better man, and a week after we got back together, she went off and cheated on me with a complete stranger she never met before (at least to my knowledge. I'll be honest and say I still had feelings, even tho she cheated.. twice.. She still wanted to be friends after that, and I thought I could do it, but she would always be on my mind. Now I got a new girlfriend, but I still can't stop thinking about my ex, I know I dont want to be back with her, as she's given me so much pain. but she did have a smashing body, with more so tits.... all Im saying it's easy to think of it, and get turned on, even though I dont want to, and I know it's wrong, and it makes me feel bad because my current girl doesn't know, (and I dont think I'll ever tell her). This is also the main reason I cut my ex out of my life, so that I can stop thinking about her, and start focusing on my new relationship.