I'm not that heartless man.yah so do what is best for you, nail her and send her back to her bf, than everything is fine
Step 1: stop calling her a "chick".There is this chick I met 2 months ago.
just be there for her man,dont push your feelings on her. Its not the right time.
Tell her kuk like she is better off without him which is not untrue
Dont sleep with her even if you have the chance.