How can i help out my friend?

she thinks shes in love but she doesnt relize that they the person she likes is only abusing her leaves her with bruces and even once with a purple eye. he almost got her pregnant he only likes to have "fun" and i feel bad for her... also when shes like spending time with other guys and not doing anything he gets mad and beats the people up! he think he so tough... and he goes around telling people he hates her but at the sametime he does anything to have with her!