In law is terrible

ok so my husband's grandma is very controlling over him and thinks she's always right. she's an ex nurse and anything medical she thinks she should handle and everyone else is wrong and has argued with doctors. she has told me that I can't do certain things with my husband simply because she doesn't like it. and over the past two days he was in the hospital because he had developed gallstones and ended up needing surgery for it. she argued about the diagnosis of gallstones, the nurse admitting him into the hospital asked me if I was his SO and she interrupted and said "no she isn't" in a very rude tone. like excuse me he's my husband that makes me his significant other! he told her not to ever come to the hospital because he honestly was in too much pain already deal with all the arguing she does with everyone. then she had the nerve to get angry that he asked for me to go with him to pre op. then she wanted me to leave! am I wrong for being upset with her? I know she's his grandmother but she's really pushing it with the things she does and says.