Hi there,
First of all, I'm really sorry you're dealing with all this. Being a single parent is hard enough without the emotional ups and downs revelations about an ex (and especially an ex like that, with so many secrets and lies) bring....
I know what I'm about to say isn't what's usually done and I'm truly not saying it in any way that is judgemental in the slightest; I'm saying it as a woman who's experienced first hand the kind of upset and mayhem such men can put us through: If I was in your shoes, and this is just me here, I would stop. I mean I would just stop everything; I'd stop talking to him on the phone or via text or with any other way, I'd stop talking to people who know him and who want to talk about him, I'd stop the CSA issue, I would just....stop. I would distance myself from everything about him and give myself the time and space to get over this and move forward. The internet is a very awkward medium, so I'm not sure how what I'm saying is coming across but I assure you I mean it in the best possible way and am only saying it because....I've been there and been through it and when I did go through it I almost drowned...
I firmly believe that you adore your son and are a person who wants to be well and live a good life. It just sounds like you're not over this man and what he's done to you and your LO (and I'm not saying you should be over this man nor am I saying that what he's done isn't horrifying) and more importantly it just sounds like this guy's presence in your life (even when it's not immediate, but like the online stuff you're saying) is toxic for you and your mental health....
I really wish I had a magic potion that could make all women instantly get over men who are such gigantic idiots that they would abandon their child and their child's mother and that there could be a way those same men could get their heads conked together or something in hopes their brains may move a little bit and they might actually become decent human beings after that...
In the absence of such a magic potion, maybe the answer is to erase such men from our lives, find comfort in our children, our extended families and friends and to just try and do the best we can for ourselves every single day....
Loads and loads of hugs....
Zondon