Your kids need to be deprogrammed sooner rather than later. Many people are estranged from relatives for all sorts of reasons, a good therapist can help the child deal with that if it happens. Preserving your marriage and your family relationships has to take a back seat to making sure your kids grow up mentally healthy.
FWIW, we quit attending meetings very abruptly and our older boys adjusted pretty quickly. They started public school for the first time (we homeschooled before), we started celebrating every holiday and birthday, they joined the scouts, and they've made new friends. We've discussed the various things that they learned at the hall and explained how the scriptures were misapplied or twisted, and we've explained some of the actual history of the WTBTS and the crazy ideas that Russell and Rutherford preached. I'm pretty much an atheist at this point, and we've talked about that.
I realize that I don't have the same experience with family members who are still active, since we only have one aunt & uncle who are dubs and they live 600 miles from us, but I still feel it's important to let your kids know exactly what you believe and why, and then act in harmony with your beliefs.