Gabriel - you sound like you're hurting. I'm sorry this has happened to you.
When I read in your letter that you have your son half the time, I thought wow, that's a lot. My H only thinks I'm good enough to have my kids 1 day a week and then I have to follow exactly what he says when I have them and put up with him talking down to me in front of them.
He's giving them a really bad impression of how men treat women and when you said half your son's days, I actually thought that was good.
At least she's not using him as a weapon. That is something to think about.