Set in the 30's or 40's, made in 70's I think, loose girl meets nice boy, date, boys from before try to rape her, end up killing her, the boyfriend finds them in pool hall and kills a couple of them.

Buster and Billie (http://www.imdb.com/title/tt0071258/)

Thank you very much. Remembered this movie and thought would be good to have.

You're very welcome.