PLEASSSEE READD!!!! its a relationship prob?

ok so ive known this girl since i was veeery little. but she moved and i hadnt seen her or heard from her untill about a year ago. im 22. and since shes been back weve been talkin and stuff as friends and she would flirt with me vise versa and then she got a bf as did i with a gf. and evn then wed still talk but as friends and then one day my parents were at her parents house for a party being thats how we met so long ago, and i went over o say hey to her since i havnt seen her in a long time, and her bf was there so it was kinda akward. but when i was there i could tell she has feelings for me by the way she lookd at me and acted and then when i left i didnt hug her or anything cuz she was taken. we txted after i got home and she said she really wanted to hug me goodbye and stuff. and weve been txtin on and off everyonce and a while since. but about 2 monthes ago she broke up with him and i can tell shes interested in me. but heres the prob. i have a gf still and have had one for about a year and a month. and im head over heels in love with her and i think shes the one. but ive liked this other girl before i started dating my gf now. and idk if i should risk anything to see if i feel anything with the other girl or not. what should i do?