My girlfriend is REALY upset, how do i help her?

ok, im just got with a new girl, and she realy is amazing, shes beautiful, caring, smart, shes perfect. but before me her ex's treated her realy badly, one of them , basicly beat her up because she wouldnt let him, and his mates! have with her. and the one after tht, decided to hither over the head with a concrete block!. now heres the recent problem, we were meant to meet up quite late the other night, and she didnt trun up. i spent all night worrying about her, because i heard nothing from her, now i found out tht morning that when she was on the way, her ex that beat her up, deciced to go up to her with his stupid friends, start touching her, then told her if she runs to me, theyll "hurt" me as they put it... so she just let them beat her up -.-'. i dnt wna get beat up by a group of people as much as any guy, but id rather of took it than them hurt her... now, shes obviously really upset, i want to know how to cheer her up without pissing her off... and also, i dont know what to do about this guy, hes allways with his buig group of friends, and even if i managed to get im alone to kick the **** out of him(which id LOVE to do >( ) hes the type of person to either stab you or something, or even worse, hurt her... i dnt want him to get away with it but i dont want to cause more problems for samantha. any help on cheering her up and what to do?