I am confused, you keep complaining that this grandmother was not there for your children all their lives, etc,. but in your first post you said, "When my boys were 11 and 12, I got a phone call from my brother, that my ex mil called him trying to reach me. I was now in another state with a new last name. She claimed that her youngest DD asked about the boys, and that prompted her to call. I spoke to a therapist at the time, and he recommended that the boys would be better off without her. Since she hadn't been there for the past 10 years and there was no way to guarantee she would stay in touch we should decline."
So, she did reach out to you. You are the one that prevented the relationship because you had no "guarantee". Well, it MAY have been a good relationship you don't know. Point is, she did try, and you rebuffed it. I know it was on a therapist's advice, but it's not really fair to hold that against her now. Whether she says she contacted you because her daughter suggested it or whatever doesn't really matter. Maybe she just used that as an excuse.
I'm just trying to say that maybe you can find it in your heart to cut her a bit of slack because MAYBE she really did have good intentions all those years ago and MAYBE she feels you prevented her from being in her grandsons lives.