Although I've read through this thread, I haven't posted till now because, quite simply, I was so gobsmacked by your son's attitude and rudeness, I was rendered almost speechless.
And call your self a grandmother, you cant pick up having the kids and drop them when you feel like it Actually that's exactly what being a grandmother is. Not having the freedom to pick and choose when you have the children is the parents' role. You've been there and done that when you brought your children up. Now it's their turn. Hence that time-worn saying "it's lovely being a grandparent - you can give them back!"
they dont want people to know how they are with me because, deep down they know its wrong. Well, that says it all, doesn't it?
Do you know what? As I've been reading your account of your son's behaviour, particularly your post at 02:07:08, I have really wanted to punch him. Sorry, I know he's your son, but he is nothing but a nasty, selfish bully.