I don't know how I missed this post, made so long ago now. I just wanted to say that I recall chatting with you around the time you made this post, and that, at that time, I was under the impression that your story was totally different than what I see here. I had no idea it was like THIS.
First, you're neglected by your Mom, then you're made vulnerable to that perp Uncle of yours who was not only sexually abusing you, he was threatening your physical well-being as well. Takes a lot of guts to threaten a 6yo kid huh? Could I have a nice tall glass of PTSD with that? Then, AFTER your Mom figures out what was going on, she LETS IT CONTINUE. You got a SHIT deal. You're dealing with MANY different elements of abuse here, and they're all bad, except for one.
The ONE good thing to consider is that you're not festering in silence anymore. You're out in the open and talking about it with groups, a therapist, and your Grandfather. (you mentioned a Grandfather, is there a Grandmother in your life as well? Just curious) This is good BECAUSE all this crap you have to deal with now won't have the same impact on your life (trust me, all the older guys here will agree with me on this) as it otherwise would if you just let it go on unaddressed.
What gave me pause was when you mentioned your perp Uncle being the exact same age as me. I REALLY hope that you find the nerve to confront this piece of shit perp Uncle of yours one day. There is a place for people like him.