Any advice

Lately my boyfriend and I have been getting on each other’s nerves over the littlest stupidest stuff. He’s a year younger and is still at home with his parents (he’ll graduate next year and I graduate this year). It all started when he got in trouble and had a long talk with him mom and he’s told me “don’t bad mouth my mom” I wasn’t going to. He’s the one always telling me she’s a bitch. Anyways I went to his house today to get his wallet because he forgot it. His grandma started talking to me and was talking about his mom a little. And I was just like yeah shaking my head because I didn’t want to get into it and didn’t care that much. But his mom texted I’m saying I can’t come over anymore because I was trash talking her. All i said was that i was upset because she said he can’t come over because she thinks my dad is a bad parent. She said she’s lost more respect of me. I didn’t do anything

Any advice of what to do?