Mrs D, could you make a sig line with your info at the bottom. It helps everyone know the basics of the sitch. It's hard to keep track of everyone.
I think the best thing you can do at this point is NC. Your H seeing you right now is only going to bring back old feelings just like it does for you but his feelings are negative right now. You want him to be able to forget those and right now when you're still spinning a bit and not sure-footed in your responses, your chances of hurting rather than helping are high.
Also seeing you might cause him to have feelings he doesn't want to have and therefor he will try harder to shut those down. Stay away from him.
Phone calls with son to H, don't talk to him when son hands you the phone unless there's something you need to talk about. Would this be a 180 for you? Or tell S, "When you talk to dad, you can hang up when you're finished unless dad asks to speak to me."
About the friends texting to H when you were there reminding him of "good times" and you telling them what to say. Manipulative. And probably had the opposite effect causing him to raise his guard against you even more. Involving friends in this is usually not helpful.
You've got some work to do to fix you but it can be done. I know, I did it and my history was much longer.
I'll mention another book-"Dance of Anger" it's old but may be helpful to you.
Me 57/H 58 M36 S 2.5yrs R 12/13
Let me give up the need to know why things happen as they do. I will never know and constant wondering is constant suffering. Caroline Myss