What would you do?

I met my amazing boyfriend this summer and we've been together for a few months. It's long distance, but we're going strong! Before him, i had been in a serious relationship where the guy cheated on me multiple times. It's hard for me to remain calm when my current boy talks about his girl friends, but i've been doing a good job. i haven't freaked out or anything. 
recently his friend (let's call her G) called him up out of the blue after being MIA for months. He was on the phone with me when she texted him, and of course i let him go to talk to her. that was his friend. i was excited for him. well maybe once or twice since then he's left phone calls with me just to be on skype with G. he talks about how he teases around with her and stuff. i know he's kind of a flirt but he's honest. 
but what do i do? i could tell him to not answer her skype calls if he's already on the phone with me. but that would result in him not calling me in the first place. i could always tell him not to call her at all but 1) i'm not that kind of girlfriend and 2) he would anyways. i know i don't control him but it just makes me anxious because i've been cheated on so much. if i bring it up he'll say i'm worrying over nothing... idk. what do i do ladies?