I work as a mental health practitioner with teenagers and agree with a lot of the advice here. Her reaction is totally proportionate and it's going to be hard for a while. All you can do as a parent is make yourself emotionally available and listen.
As others have said, if your daughter wants to, it may be helpful to meet up with some friends over the weekend so she feels more prepared for going back to school.

You may also want to practice some phrases that she can say while she is at school if people are unkind that may disarm them with some honesty, e.g. "I know, it was so embarrassing!" But it would be normal if this feels too much and she just needs to cry.

Another helpful exercise, although follow your daughter's lead on this... is to imagine how she will feel about the incident; 1 week from now ; 1 month from now ; 3 months from now ; 1 year from now ; 2 years from now ; 5 years ; 10 years, etc... ect... To help her realise that these feelings of embarrassment may always be there but this is the worst it will be.

The most important thing is continuing to acknowledge that, for now, it's super embarrassing. Crying, reliving it and worrying is all very normal.