Overcome, no wonder you feel conflicted. Personally, my daughter has not done a thing with all her manipulation to earn my trust. So, I don't spare the reality of it all when anyone asks. I covered for too long because of denial.
It's important to choose to use our battle energy wisely. If you put yourself in the middle, everyone will either hate you, blame you, or hold you responsible for their own undoing. If it's important that these people-who you owe nothing-know the truth, then I understand the temptation. I also understand that the histrionics of your son's behavior may be important information so others can avoid his manipulation and possibly help him, instead of enable him.
I am on a fresh wound right now from someone reaching out, a family member of my daughter, wanting the help, but what was really happening was my daughter was running out of people to take advantage of. She told horrible lies about me, I am certain. In the end, the whole thing led to weeks of me spiraling downward. What the person really wanted to do was tell me what they think I should do, with no idea of the horror I have managed to live through over the past 15 years. My wounds may be too fresh to offer the best advice. What I can tell you is that I made a decision to stay out of middle of anything. Sometimes ignorance is bliss. The fact is, all that heartache didn't change one thing. Best of luck dealing with such a precarious position. I am thinking of you.