Nope - I had one but she was a horrible lazy bitch. Thankfully she is gone now , and the only good thing was that she left the two children with my son who is now a single father and has sworn off women.
You don't give any details so it's not possible to talk about your situation . I can only hazard a guess that since you say "she is pregnant again", that she is still with your son and they are still making babies.
From my own experience I'd say "Be nice no matter what happens". The nasty piece of work who was my DIL never knew that I hated and detested her - when I saw her I was always smiley and nice. I babysat the children as needed and was always friendly. Many times I had to scrub the filth off their skins and take them to the doctor with untreated illnesses. But I kept quiet about how this affected me. So now, with the separation complete, I can still talk to her occasionally and there is no problem. The main thing to keep in mind is that as the parent of your grandchildren, she holds a lot of power in their lives and in your son's life. Don't spoil your chance to be their grandparent, just because you dislike their mother.
So my advice would be "Be nice, no matter what happens - you'll be glad you did when things go bad" .
