Reopened Mind and Totally: This will pass and it will get better. I think your son is greiving too and he needs you to not break down. He needs you to take the punches. It hurts, I've been there and still am to an extent. It is getting better for me but I had to let him vent. Showing anger doesn't really come easily for him. As I have observed mother/son relationships I perceive that it works out best for the mother to step back. Usually as the dil enters the picture a power dynamic starts to occur. When a male son starts a family, no matter how wonderful the new wife might be and no matter how kind the mother of the son is, it still happens. I saw it with my mother and her mil who were not JW. It happened to me twice (my son is remarried) and I wasn't surprised. I was hoping it wouldn't but it did. Of course our leaving the bOrg caused it to escalate.
I think the best strategy is to get on with and enjoy your life. You know you did a good job. He knows you did a good job. Give him the space he needs to heal. Let him see that and let him see that you are okay taking his punches. This is not a time to cower, for long anyway. Accept that your relationship is going through some changes, this is probably the worst it is going to get.
From what I've read about you and your husband, you're doing all you can. You're doing everything right. That's all you can do. Your son and dil don't realize what a gift you are giving them. Stand tall and let them see you succeed. Keep showing them love at any opportunity, they need it but don't let their lack of appreciation get you down.
I wish you the very best and I know it's going to get better.
K