Well I was in a similar situation as you were about two years ago. In middle school, I had 3 best friends, we were together for three solid years //one i knew since i was elementary though//, when high school came around, we got into a huge stupid fight at one of our Bday parties--which I started sadly because I was getting frustrated how they were treating me like shit every single time. We acted childish and I do take some of the guilt because at first I thought it was all on them. One went with me, the other two went with eachother.

During high school years, my one best friend because my lover and the other two just became closer; During senior year, something hit me because everytime we saw eachother we missed eachother, we all connected but hated eachother. One of us wrote a story about the worst incident of our lives, it was that fight. Slowly one another started to talk and we all sat down and just said "we were young, stupid. Things been said and can not be erased. I just want to tie up loose ends because it's a guilt that has haunted me". We act like we are all still best friends and nothing happened even now.

--Anyway, I think if it is really bothering you this much, you should confront them, just tell them how you feel, what has been going on through your mind, even though you don't plan on being friends again, that you just don't want to leave a bad impression on them for the rest of your lives. :3 //I hope things get better <3