Possible OCD & Distorted/False Memories from Sexual Experimentation ?

Hi everyone,
So I've stumbled across this forum and decided to post a personal story in aids to get some advice and help from anyone who's experienced similar issue.
Long story short, I was involved with some weird awkward sexual play/experimentation with my younger brother (5 -6 years younger) when we were young. My memory is really distorted and I think I was around 14-16 yrs old at the time. It wasn't anything serious (as far as I "remember" just some slight rubbing/dry humping in the middle of a wrestling game that went on for no more then 30 seconds - 1 minute. I don't know what possessed me to do it but probably onset of hormones, curiosity and the feeling to "scratch an itch". I regret it with my life and I feel terrible that I would do something like that. I don't recall forcing or coercing and this happened once or maybe twice. Was never intended to harm my little brother as I would hate to know that I have harmed him in any way. Fast forward more then 10 years + and I've been all of a sudden hit with feelings of guilt, shame and disgust with myself, not to mention anxiety and depression as a result.
What Im struggling with is why this memory has been played on and off for the past years as something "weird" that I did and all of a sudden its like a huge evil sin I've committed that has been potentially traumatized my brother in a way ? I've always been bothered by this "memory" but never gave it much thought other then shame. Now my mind has latched onto it and made me feel like my whole life revolves around this incident. My issues are:
- How can I deal with the shame and guilt that my mind has become obsessed with ? I regret it with my life and I feel like its the worst thing I've ever done and not able to achieve full happiness due to it
- Constantly replaying the memory in my brain to figure out exact details of the incident to try to resolve it between abuse or innocent experimentation. Im not confident in fine details but it feels real that some sort of weird sexual thing happened
- Knowing which details are real and which are false and distorted ? this has been tormenting me from morning to night all day for the past 6 months almost. Up until then, its never bothered me as much. I know sometimes people can create 'false memories' but if this is indeed mostly false then its really messing with me cuz it feels super super real.
- Anxiety on trying to determine if my brother remembers and/or if hes affected by it. So far this current day our relationship has been getting a lot better over the past 4-5 years compared to our days of fighting and sibling rivalry. He seems to be comfortable around me and he initiates most of the contact. However, Im always worried how he really feels on the inside sometimes. People I've told tell me he seems better happier in life then I do but I always have the gut feeling of worry and uncertainty.
And one more thing that I question is that from the time that I think the incident occurred until the first time that I "remember" remembering about it, it seems like a long time. So it bothers me into thinking why all of a sudden my mind has decided to become bothered by it and constantly ruminating about event and seeking assurance that Im not a sick perverted sex abuser or something along those lines. What I did will never be repeated and it is totally against my character.
if anyone can provide some insight I would greatly appreciate it and if someone has dealt with similar issue, how did you deal with it and hopefully overcome it ? Thank you so much in advance. Im really struggling here and could use some help.