Not one of my proudest moments.... throwaway for obvious reasons. My first love was a tumultuous one, as many of us on this site know all about. He inadvertently fed my insecurities, I more than happily fed his god complex, a smorgasbord of delusions to be had. This was Freshman year of college, and I'd never been in a relationship before, so I was taken aback by the depth of emotion, and fell hard. He was also new to the relationship game, but held his cards close to his chest. We dated the second half of the year, although we met the first week of classes. We split up after a suicide attempt. After I went inpatient, he stopped talking to me. Classes had ended, and he blocked me on cell. I wasn't ever super into social media, but he blocked me on FB. I felt so alone, betrayed by the first person I had ever opened up to. It felt like overt cruelty, and I felt I'd lose my mind, going back in forth in my head, wondering whether or not he ever loved me (for the record, I now understand why he had to leave, we were deeply codependent and though neither was malicious or abusive, were harming one another).

I got help, finished school at a different college than the one we met at, and managed, despite never really addressing the BPD issues. I did some rounds of DBT, and rural state inpatient scared me enough to divert future attempts, but my eating disorder worsened and I had to switch priorities from BPD management. 
Somehow I managed to get a degree with a decent but lower than potential GPA. I move to work at a company located in a state a lot of my family is from. Problem is, his family is too. I wasn't that worried, because although it's a fairly small state, we live on opposite sides. 

I was recently dreading the upcoming family gathering and drowning my sorrows in liquor at some swanky hotel bar. Seeing another person drinking a few seats down, I sparked up a conversation. About ten minutes in, after flirting and offering to buy him a drink (I'd already reached my limit) he asked me my alma mater. When I replied, he said, "What a coincidence, my son went there too!" When he said that, my blood runs cold. I saw it then; the hairline, delicate slant of the nose, and prominent jawline. I didn't even need to ask the son's name, although I did. My suspicions were confirmed. I ordered a double to go, asked him if he was staying at the hotel. Apparently there was a dental convention in town. We fucked and I left before he woke in the morning, to get ready for brunch with my family.

I feel sick with myself, my behavior. I'm absolutely ashamed, and keep thinking about how I fucked up Christmas (as stupid as this sounds, I think the holidays somehow makes it worse). He wasn't wearing a wedding ring, but I did some digging online and they're still married. We didn't exchange numbers and I left before he woke up, but I'm revolted with myself. I just don't know what to do with this secret, I'm compelled to apologize to my ex even though I logically know that this is a purely selfish and sadistic move. What is wrong with me?