i don't want her to stop talking to me because I'm contacting her too much
Most Helpful Girl
Give up, you can never win - she will either a) choose him b) choose him AND tell him you're messaging her - some girls love their men being jealous and this will cause problems for you c) laugh at you as she thought you understood it was just friendship. d) start to see you behind his back or e) dump him for you
She is with him because she WANTS to be with HIM. If, in the unlikely event she went for option 'd' or 'e' then she is a girl with no morals and would go behind your back or dump you the second someone else caught her eye.
Find someone else and don't have tunnel vision on this one girl, I bet there are many pretty, single girls who you may not have even considered before.1