I cheated on my boyfriend with his friend and my best friends ex.?

So we had a movie night with a group of friends recently and my boyfriend (of one year) wasn't there because he was sick. We were all squished on the couch really close with blankets. Me and my really good friend, lets call him Taylor(strictly friends never liked each other that way) all the sudden started snuggling and holding hands, and before I know it we were on 2nd and 3rd base but know one could see because we had a blanket on we just pretended to be watching the movie. This was SUPER unexpected and I was like omg what am i doing, because the only guy i have hooked up with in my life is my boyfriend and i thought this sort of thing only happened in movies or at least not to ME. But I have recently been losing interest in my Bf and wanted to break up with him but its hard because i obviously still care for him alot. "Taylor" and I texted after and talked about it like whoa what the heck did we just do, but im super guilty about it because its just so weird and twisted I mean my best friend just broke up with this guy 2 months ago and she still likes him! ahh and He is one of my boyfriends good friends...its messed up I know. Im so guilty and I can't tell my boyfriend because he would kill "Taylor" and If my best friend found out she would most definitely hate me!! AHH