Autistic husband "wishing" cancer on my sister

My mom doesn't really like my husband. He has autism and can be overtly blunt. I have told him to work on thinking before he says things because he will say anything that comes to his head. He's very... Honest. What my mom is mad about is my sister is facing legal consequences for charity fraud because she was caught faking cancer. I don't really talk to my sister so when I found out she "had cancer" I didn't really keep up with it. I did donate like $20 to her gofund me. Well she doesn't have cancer and my mom was the one that told us because she wanted to know if we knew any probono lawyers. When my mom said it turned out my sister was lying about Cancer, my husband said "Oooh. Karma's not gonna like that one." She got upset and took it as my husband is wishing cancer on my sister and said we should be happy she doesn't have answer. My husband said he's glad she doesn't actually have cancer. And he wasn't wishing it on her. Just that Karma's a bitch and you don't fake things like that. My mom is just upset now. My husband apologized for offending her but she doesn't care. My family just brings so much stress to me.