Sorry to hear about your situation, You have my sympathy. However, pls don't ask your children to choose and take sides, it's not fair.
I am also NC with my toxic parents (my sister is also NC with them) due to their falling out with my gran (who we are v close to) and demanding that we stop contact with her and 'show loyalty' to our parents. We refused to do so as we love our gran v much, it doesn't mean that we don't love our parents tho, but they fail to see this and haven't spoken to us for years due to our 'disloyalty'.
The reasons that they, my parents and gran, have fallen out we (sister and me) feel don't warrant us also falling out with our gran; having said that if she (our gran) had done something terrible to our parents then we would have made our own decision and stopped contact with her.
As it happens our parents are childish, selfish, drama seeking narcs and our gran, tho not perfect (who is) has been a damn better role model than either of our dreadful parents.
I can't see us ever making things good again and dread being where you are now. The very best of luck to you, you sound v sensible.