I have been seeing thing guy in secret for a little over two years now, kind of on and off. He is actually one of my little brother's friends. No one knows we are screwing and for the last year he has been in a relationship but we still meet up to do the dirty on a somewhat regular basis. The sex is great and I'm really not into relationships but I am on the fence about having sex with him because he has a girlfriend. I know my morals are screwed up because I obviously don't care and still have sex with him but...idk...I just felt like I needed to tell someone so I am posting it in here. I think that he only comes to me to have sex because I don't make him wear condoms and I actually kinda get off on the fact that he cums inside me (Yes, I'm on birth control before anyone says anything. I have the Nexplanon implant. I have also been diagnosed with PSCO and told prior to the diagnosis that I can't have kids.) But I just kind of want people's thoughts on this and have you ever been someone's side piece? If you have, how did you feel about it?

UPDATE: I have read all your comments. I understand why many of you hate me. I feel the same way about myself. I came to this app to get advice on what to do, not be degraded. I have very real feelings for him and that's why I'm so conflicted about this. We started this both single and somewhere it took a turn and now it's here. I don't even know how to stop because I feel so much for him but I know that everything he tells me is BS because I know he will never leave her. And to the people who say I still can get pregnant, no actually I can't because I am sterile, those are the cards I was dealt. And I am not sterile bc of the PCOS, I am sterile because my previous doctor didn't listen to me and put me on birth control when what I needed was surgery to fix what was then not an issue and has now developed into a painful and permanent issue today.