help.. idk what to do. PLEASE READ NOT THAT LONG

i used to be best friends with this boy. He was my boyfriend's best friend and also my best friend. I had a liking to this guy but I was also in a relationship, and I liked my boyfriend better. while dating a couple months ago I would be flirty with this boy and he touched my butt a couple times. I told my boyfriend all of this because I felt so guilty and he was very mad at his friend. They are not friends anymore and I miss the one boy so much I have no idea what to do. sometimes I wish I could text him but I know my boyfriend would get mad I just really wish I could talk to him still and I don't know what to do. I talk to my boyfriend about this and he said I can have one of them in my life either him or him so I picked my boyfriend. I still miss the other boy and I don't know what I should do. I love my boyfriend so much but idk if i should break up with him.