Hi Newfound,
N's will always try to get to you through your own children, which is so cruel to the child, who has no idea that they are being used. In my case, I have no children, so my N mother (I'm also NC) has tried sending letters to my husband in an attempt to turn HIM against me. In these letters she kisses up to him, tells him he's the perfect SIL, then goes on to say that she feels sorry for him for being stuck with me, that she prays I don't hurt him the way I hurt her, etc. It's SICK.
I know this would be a very difficult thing to do, but is there any way to pre-screen the letters that she sends to your son? If any of them contain manipulations, maybe you could keep the letters from him. I know that's easier said than done, because children SO look forward to letters from their grandparents. But at this point, I would try to protect your relationship with your son, and to heck with M.
As for going no-contact, Ns don't ever surrender to it. They might for a while, but will try again. They refuse to be ignored, and will fight back. It's not been easy for me, because M has found other ways to get to me . . . mostly snail mail and email, and using my father as a tool to guilt me. Just be prepared with the knowledge that she'll never give up. Ns will never allow themselves to lose control. Just when you think things are going well, she'll be back.
Wishing you all the best with this. Do whatever you have to do to protect your son from being used as a pawn in her screwed up game. It's reprehensible for someone to use a child as leverage, but they do.
