What do i do????

i have a best friend who ive known for 8 yrs and he is going out with this girl who is just completely the sweetest person you will ever meet and the problem is i like her as well and she likes me too WHAT SHOULD I DO i hang out with her at lunch with one of her friends and my best friend WHAT DO I DO?!?!?!?!?!?!!? also we call eachother every night at 730 pm and talk for an hour and a half every night. we both have feelings for eachother but i dont want to steal her from my best friend......... plz hlp