Is this worth fighting for?...Help plz!?

ok so i've been dating my boyfriend for almost three yrs and recently this girl who apparently is a sl*t went around and told everyone she gave my boyfriend a bj also she freakishly got his # from someone and started textin him that she loved him and that everytime she saw us together she wished she was with him instead my bf called her crazy and to stop textin him she said what about our time together??? stalkerish bc he's only met her one time in a parking lot hangin out with his friends when hr and her friend came along and her friend flashed them ewwwwww....anyways i confronted her cly about it didnt cuss threaten anything short and sweet why are u spreading that rumor she acted completely oblivious to it blank look on her face didnt know what i was talkin about and just walked away bc someone called for her...whatever i wasnt gonna chase her down and ault her i just maturely left...then a while later after she got fired from her job for saying she got with all the workers in the parkin lot on breaks she decided to drive by me and my boyfriend in the parkin lot smile at him befor i knew it was her or what was goin on (i'd never met her before the night i confronted her)and then she flipped me off three times across the parkin lot in her car as she was drivin away...wtf....i couldn't do anything other than run across the parkin lot after a moving car NO WAY i'm really drama free and i hate this kinda thing but if she did that again or got in my face what should i do? i'm seventeen and i know shes either 18 or older what kind of trouble could we get into?