My fiancé has erectile dysfunction. We're both very eccentric people and aside from our sex life, everything in our relationship is absolutely perfect. I can't imagine anything better. He's my best friend, I can talk to him about everything. Including the fact that I've started to fantasize about his best friend, CF. I told him the first time it happened. We hadn't had sex for months and I didn't masturbate or watch porn, out of respect for his already deteriorating self esteem. He feels less of a man because of his condition. But then one night, I had a very vivid, sexual dream where it involved CF. I told him about this as soon as I woke up. I felt like it wasn't right that I dreamt of CF and I making passionate love. But at the same time, it wasn't in my control. This was weeks ago. He was hurt by it, greatly, but he expressed that he understood. He said this was all a result of his inability to perform sexually. I comforted him and I reassured him that I would be there for him, that this won't get between us. Tonight, I tried to masturbate. But I can't bring myself to think of my fiancé. Given it reminds me so much of all the times he's gone soft inside of me, neglected, or dismissed any sexual advances I made. So as I came close to climaxing, I found myself whispering CF's name, picturing that it had been him that brought me such a pleasant feeling. All this happened while my fiancé is asleep. I feel guilty. I feel like what I did was wrong. I feel like it could eventually turn into something more damaging than me thinking of my fiance's best friend while I'm pleasing myself. What should I do?