I'm not familiar with your situation. Obviously in troubled times your parents were there for you and the children. It seems as though they are paying a huge price for their loyalty to you. In the true nature of the Christmas season, and year-round, keep in mind Galatians 5:22-23.
Galatians 5:22-23
22 But the fruit of the Spirit is love, joy, peace, longsuffering, gentleness, goodness, faith,
23 Meekness, temperance: against such there is no law.
I try to keep these nine qualities in mind as I go about my daily life and find that things go much better when dealing with others. Perhaps your husband can drop his bitterness and subscribe to these qualities so that everyone may have a very merry Christmas.