Desertrose, I agree that seeing or not seeing his kids will not make a difference in his addiction. I also agree that your decisions should be focused on what is ultimately best for you and the grandkids. Speaking from personal experience, my grand-kids have always been my downfall into enabling & taking on responsibilites that are not mine. I need to put the focus back on me. And hope that you will do the same.
Hugs,
Chris