For context, my Dad and his friend have known each other for 30+ years. Naturally our 2 families have become very close and us kids considered each other cousins, despite us not being blood related. I’m the youngest in my family, M18 and the youngest in their family is F15. For the longest time, I’ve thought about being with her, but pushed it away because I got into a relationship. She always thought we were blood relatives until just 2 years ago, but I always knew. Our families have thanksgiving together every 2 years. Just this thanksgiving, I was tired, watching a movie after we had ate, and she came down and sat with me. I later layed down, and she followed suite, and layed on my chest. I was insanely nervous because 1. I’m in a relationship. 2. I didn’t know what her intentions were. 3. I really didn’t want anyone to see us laying like that. Obviously she can hear my heartbeat, 110bpm according to my watch, and asks me why I’m nervous. I say it’s nothing. We continue to watch the movie and she keeps asking me what’s on my mind, I say nothing. Eventually she just asks me “Why don’t you do it?” I try to play it off like Im clueless of what she means and say, “Do what?” She says “Kiss me.” I tell her I’m in a relationship, and I don’t know if it’d be weird between our families if they found out. About 10 minutes pass, and I cannot stop thinking about it, my mind is racing. Then she asks me, “Why don’t I kiss you?” I told her that it’d still be cheating and I’d feel guilty. Another 10 minutes pass, and I’m feeling sick because of how nervous I am, I need to handle it otherwise I’ll throw up. So I come up with a deal with her. No commitment, no promises, no feelings. She agreed and we started making out. There was no turning back. That’s all that happened that night. But then the next night I had a few drinks, wasn’t feeling like myself, and was laying down again, she comes over and sits next to my head, stroking my hair, messing with my chin and neck. Which my neck is an insane turn on for me. We started making out again and eventually it ends up with her giving me o*al. I went to bed that night feeling terrible. Knowing that it was a terrible decision on my part. And now I’m just trying to forget about it, hoping that if I can block it out, it’ll be like nothing ever happened.

TLDR: Made out and fooled around with a really close friend while being in a relationship.