This is no easy by any means, so be kind to yourself. You are entitled to whatever feelings you have right now. It’s great that your grandchildren have you as a support and you are healthy and well to give that support. That in and of itself is not a given or a fall back option for many. Your grandkids have shown strength and resilience…..they don’t wallow in self-pity about what happened.

As for why your daughter and grandkids turned out the way they did, there is no easy explanation at all. Hindu religion and its concept of rebirth offers some explanation that may be of consolation. Too much to get into here.