Who could ever understand the narcissism of this mother? Are there suggestions how my husband should react?

always been selfish as attested by siblings & nieces love him & said he was great to his parents. Mom preganant before marriage. She & her deceased husband never attentive. Had negative conversations about him with his ex wife, who they swore they hate.She lives out of town. Stayed with us & her brother.- who said she yells at him. Gave money to my husband's children, told him twice he gets nothing. He never asked her for a dime, wants nothing. She's wealthy. What a thing to say Leaves phone messages saying he's a bad son.We begged her to come for summer & always welcoming. She's 73- goes from MD to MD claiming chronic pain. when she was here, went to Broadway show with ex wife & grandkids - made them promise not to tell their father.Daughter told him after the fact, & said grandma talks meanly about him. She told her not to talk about her father. Daughter& dad are very close. He is so hurt. Has talked to mom calmly of his hurt- says she is sorry-then starts again. ISuggestions?