Thoughts???? Has anyone had a similar situation?

I met a guy at a kickback& I was instantly attracted to him. I made it my goal to simply talk to him by the end of the night. Well, I got pretty tipsy and found the courage to talk to him. We talked and eventually found our way out of the house, in his car, hooking up. I was definitely not expecting to have sex with him that night. I knew I wanted to see more of him after that night & I did see more of him. Well, being my 19 year old self, I looked him up on social media, found his Instagram and low&behold; he was ENGAGED. I felt hurt but told no one about this because of the advice on morality I was going to get. So I played dumb until I felt like it was time I told someone. In the meantime I was still seeing him, secretly knowing he was engaged. This was the first time anything like this ever happened to me, I realized that I loved the adrenaline I felt while being with him. Eventually caught strong feelings for him. He would text me at 2am-3am almost every night to see if I wanted to "hangout" and me being so naive, I drove to him. I would constantly look at his Instagram and see his posts with his fiancé. I had enough one day and told him I found his Instagram& threatened to tell his fiancé if he didn't tell her he had been cheating on her. Well, it didn't work out in my favor. I thought it'd be me with him in the end, but his fiancé stuck by him. He privated his Instagram, now I know nothing of him. But I don't feel bad about him cheating on his fiancé, for me. I don't know why.