Girlfriend is Jealous of My Friends

My girlfriend always gets upset because I talk to my friends. For example, my best friend is one of my exes from about 2 years ago. Ever since we broke up we have been best friends. I have known him for about 2 to 3 years. Well she has a big jealousy thing going on because I talk to him and everything. I told her that she has nothing to be jealous over because we are just friends, we tried working on the fact that she gets jealous too easily and she has been okay with it, but when she has gone a day or two not getting mad and jealous, then she usually blows up in my face from holding it in for too long. So I need some advice on how to keep our relationship going. I love her so much but i mean I don't even get nearly as jealous as her.

For example there is this chick trying to get with my girlfriend and i don't like her because of it. See I told her that I didn't want her talkin to her because she has caused out relationship a lot of problems. Then my girl told me that if she couldn't talk to her then I couldn't talk to my best friend. I told her that it wasn't the same because that chick is TRYING to get with her and me and my best friend just talk mostly about our relationship problems, but she still won't let it go.

What should I do about this? I don't want to break up with her or anything. I just want to make it work. Should I stop talkin to my best friend or what.. Please help me on this.

p.s- im bisexual and my girl is gay. That's probably why this sounds weird. lol