Helppp!!!

Hi... I am bi (only out to a few ppl) and I'm a teen. I have not yet been in a full on relationship with a girl... but i have a story...

I was in a play and I met this girl (she is pansexual) and we were gossiping for hours and had so much fun. I kinda caught feelings... I cannot stop thinking about her... but there is just one problem... She has a boyfriend...

I have no idea what to do... but she flirts wih me every day and i cant tell if she is actually propa flirting or shes just really nice... helppp xxx