Point that out to her. She may have a boyfriend now, but you are her family too.

I re-read that, and I didn't mean to sound like I think you are being stubborn. But if you try to talk to your Mom and put everything on her, she may get defensive and it may turn out worse. I used to have to talk half of the blame with my Mom, then she didn't get as defensive and would bend a little more.

Do you have a close friend or someone that can do somethings with you? It is your special day, it should be good memories for you. Not memories of fights or hard feelings.