What should i do about this crazy situation (prom related )?

So I'm going to prom and my mum wants to come and watch. No one I know has parents who are going to watch and I know she is going to make the event about her. As she always does but I objected to the idea and now she's upset and I feel bad what should I do? Also is it even normal for parents to watch I don't want her to go but I don't want her to hate for objecting...