Ribbons Rainbows and Roses - I am so sorry your son has done this to you. Know in your heart that you did everything you could as his mother and take no blame or guilt for his behavior. Since you returned home your posts have been very positive, and as long as you take a positive attitude your life will be so much better. Your therapist is going to be a big help in keeping you on the right track. If we lived in the same town I would be there for you as a friend, it would be great to sit down and talk instead of having to communicate through the boards.
What is even sadder than the things he has said to you , is to cut you off from Jasmine, the granddaughter you love so much and want in your life. You don't deserve that. Your son has no loyalty and obviously he is allowing his wife to run his life. Perhaps when he matures and becomes a man he will find the strength to stand up for you, his mother, in the meantime you will stand strong and live your life to the fullest.
As for your will, as ennui1 suggested, you can leave whatever you have to your granddaughter in a trust. Your therapist should be able to point you in the right direction for that. Take care of yourself, you come first and I wish you peace and happiness.
The moving finger writes; And having writ, Moves on: nor all your Piety nor Wit Shall lure it back to cancel half a Line Nor all your Tears Wash out a Word of it. Omar Khayam