Judy, I completely understand. I have a 12 year old granddaughter and sometimes I just want to throttle her
She NEVER acts out when she's with just me, but when she's at home, she can be a little twit to her parents. Makes my jaw drop to see/hear the things she does/says.
Sometimes I think they are too hard on her though - I remember picking my battles with my daughter, I let some things slide because I just didn't want to fight that battle. My daughter and sil make my gdaughter tow the line and sometimes I feel sorry for her, but I can't say anything.
Anyway, she loves you, it will be OK and she will make up with you. It may take a little time, but she'll be OK (and so will you)!