I think you did great. This is H's issue and they probably don't know what to do or say. I know my MIL wavers and supports me one day and then H the next. H is her son and she will protect him, but deep down she knows what he has done. Read my sich...I had an issue with MIl just this week.
You are showing yourself to be the bigger person. Good for you.
Me: 46 FWS: 36 Married and Divorced 4/07, Pregnant 7/07,False R 7/07 Baby Girl born 3/08 Kicked him out because OW: 7/08 5/10 He realized what he had and lost. Moved home! REMARRIED 3/14/11!!