I agree with B2Y....you have every right to be hurt by this behavior. These situations do bring out the worst is folks. Guess it's their guilt making them behave badly.

Getting all stressed out won't do you or your MIL any good. She knows who's been with her in good times and bad. Believe me, she knows.

Just take the high road and show those fair-weather family members how a "real" family member behaves. It's hard....probably one of the hardest things you'll ever do. But the One who's most important will see it all.