People are doing really bad things to my friend how can i help her?

Meghann we got in a fight and she got over it and i bought her new pants from hollister for $60 and now people at the pool are spitting on her including the life guards and they spit in her pop and they told a bunch of rumors about her and people that where her friends stated doing it to so im going with her tonight and they will be there and there going to keep doing that what do i say and how do i defend her they keep pushing her around and its getting old and it needs to stop!!! PLEASE HELP