It's okay to feel the way you do. Jealousy is a normal human emotion, and it's easy to feel it when things aren't going so great. I don't think you need to be so hard on yourself though. Since you played such a big role in your grandchildren's lives, it's okay to take some credit for amazing they are. They needed you when their mom wasn't able to be there, and you were.

Also, I don't believe anyone has the right to judge you. You tell us a lot of the story, but not the whole story, you don't deserve judgement.