Bestfriend got a lover Syndrome!

So heres the deal. My capricorn friend from Highschool year of 2004 and I have gotten very close over the years.
We are literally the types to speak everyday to update eachother on EVERYTHING!!!
She has been out of a relationship with her BF for more than 2 years but they still kep in touch-Everyday I get a simple update about them and their non progress. Let me not come off one sided-Myself and My girlfriend have been off and on for a year and a half. When we are having a rough time shes always there to talk to but i kind of feel like thats her enterainment! Before she and I were off, I started to feel drained by my Friends contant gossiping about her other friends mishaps, relationships, her ex, and complaining about work. So when My girlfriend and I got back on she text me with the, Everytime Your with her you never could be found.
I get calls back to back, if I dont answer, I get "im guessing you didnt get my call"
Now my friend is very straigh, I do not see her having any love interest in me. But we work together different floors. but we text alll the time, and speak on the phone (not nearly as much as before) all the time. BUT WHY CANT I ENJOY MY GF WITHOUT FEELING BAD!!? OR HOW CAN I GET SOME SPACE WITHOUT HER THINKING ITS ALLA BOUT MY GF? IM DRAINED AND ANNOYED BUT I DONT LIKE FEELING LIKE THE BAD PERSON.
PLEASE HELP
CANCER FEMALE-WITH NEEDY CAPRICORN BEST FRIEND.

Its very aggravating, really makez me not wAnt to call or see them for a while...