Hi hoping4hope,
Yeah, that's a very tough spot to be in. I'm sorry you're caught on this unwanted journey. It's good that you're moving towards acceptance of where you're at.

If a grandbaby comes, keep in mind that you as grandma can be a positive influence in that child's life. Many kids who grow up in unstable homes find their stability from outside sources, and grandparents can provide that mirror of security.
GeekyGirl asks some good questions. Once you know what kind of relationship you want with a potential grandchild, you can start figuring out how you want to proceed. Also, is your son still with DIL as a couple?