Deep guilt after abusing as a kid

I have had a painful regret and thought If I shared it maybe I would feel slightly better. When I was a kid about 11/12 even 13 I cannot remember exactly, I remember we had a friend who used to stay over and they would have to share a bed together they are a year younger then me but I remember we used to play fight and such and when we made too close contact I would get slightly sexually aroused, I had not understood what that feeling was as I grew up in a Conservative family. It evolved to the stage where I would physically rub against them when asleep to get sexual satisfaction. At the time I didn't feel this was 'abuse' I knew somehow it was wrong though but regardless acted on it. Fast forwarding being 21 years now I cannot get rid of the regret that I have abused a close friend, they have drifted away from me most probably because of those earlier events and rightfully so. I live in constant fear some day I may be exposed or reported and the constant regret sometimes overwhelms me. I am a normal successful person now, with no deviant ideas and know how to control myself but I cannot comprehend what drove me to do what I did when I was younger.

Kids are strange. It sounds as though you had these emerging sexual feelings which you had not discussed and you didn't know what to do with them. Yes, you should have listened to your gut instinct, but children have poor impulse control and an underdeveloped moral system compared to adults. You are, on the very real level of brain development, a completely different person now at 21. Do you have any idea how your childhood friend is doing?