So I recruited a girl for my M.Sc neuroscience project and we ended up getting along pretty well. We talked for a couple hours and laughed a lot so I decided to ask her out and we ended up playing badminton together. Everything was going great. Afterwards she invited me to her birthday which was being celebrated in a bar downtown. I got there, we danced yada yada and we later got to her place and had sex. After sex, we started talking and she revealed she was in a LTR. I was pretty fucking mad because I liked her and also because I felt she manipulated me. Anyways, she said she felt ''bad'' for hiding that shit (her previous actions were absolutely not suggesting she was in a couple) and said their relationship was in a ''down'', but she couldn't bring herself to leave him right now because she ''didn't want to break his heart''. I know how terrible this sounds, and I also know that EVEN if she leaves him, it would be pretty stupid of me to trust her. Then again I feel like our chemistry in bed is amazing and we get along really well. I guess I'm infected with oneitis atm. Anyways, we keep seeing each other from time to time and I feel like both of us are really attracted to one another but I'm really confused as to my next step... should I confront her / reveal how much I care for her (which could probably hurt the image/frame I have maintained so far) or just stop seeing her.