What you write Aggy is similar to my own experience, and that of others here. However, there is one big difference. You see your grandchildren, you have an ongoing relationship with them. I don’t have that and it is heartbreaking. It is however, the one thing you must cling to. Fight for, but in a way that may sadly mean walking on eggshells. Rightly or wrongly, you have to accept whatever conditions are imposed on you. If that means putting up with coldness, bad manners etc, then so be it. The days of respect for those who played a huge part in the making of the man they presumably love, are long gone.
You need also to accept that nothing you say or do will change the way your daughter-in-law treats you. Especially not after ten years. Who knows why so many daughters-in-law feel the need to airbrush out their partners family, particularly the husbands mother. I’ve been a counsellor for many years, and I have seen and heard enough which, added to my own personal experience, gives me some good ideas. But the only conclusion I have reached is that you can’t win.
The person you do need to talk to is your husband. Show him this thread, google estranged grandparents. He needs to know how easily he could lose his grandsons.
I would encourage your son to bring his children without their mother, where possible. It’s probably what she wants anyway. Don’t make plans for holidays together, or any other activities which will just flag up the problems, even exacerbate them. Like I have had to do, put away the dreams of a loving, caring family with everyone smiling and happy. Just treasure the ones who love you, and let go of those who don’t.