I dont know what to do.. help plz

You should never have to choose between anyone. Unless your girlfriend has logical reasons for believing this, like one of them touching you in a way a girlfriend should, or being too lovey dovey with you. Friends of the opposite sex should probably not do that to you if you are in a relationship since that is very disrespectful on their part.
You should ask your girlfriend why she feels this way about them, what are the friends doing to make her feel so uncomfortable. If what she says can be easily fixed then have a talk with the friends about respecting boundaries.
Neither side should make you choose. It's unhealthy in a relationship to have to choose your significant other over your friends.

Girls get jealous very easily if they are in love. What you need to do is assure her that you love her more than anything. Tell her he daily, be a little romantic, I'm sure she will forget about being jealous.

I've learned with experience that sometimes those jealous pangs can be removed if you bring your girlfriend to hang out with these friends. You are allowed to have female friends; I agree with that. As unhealthy as it can be to have a jealous girlfriend, I can tell you really love and care for her, so asking you to tell her to get used to it or hit the road will not work. I've used this both ways - when there was a mystery friend of a guy I was with, I tried to meet her and just figure her out. If I had had a jealous boyfriend, I would bring him to hang with another guy and would watch them become fast friends. While it's possible this may not work for you, you need to remember your feelings are worthy, and while you can be accommodating to both your friends and girlfriend, do not sacrifice what makes you happy.

Do you involve your girlfriend with your female friends? Do you hang out with them each alone? If your girlfriend is insecure, these things may feed into that. I would try to involve her as much as you can and make her feel accepted and important - but also be firm. There is no one who has any right, no matter their relation to you, to dictate who you may or may not speak with. You have your right to your friends, whether male or female, just as she has a right to hers. Stress this to her while making sure she is included with your friends to hopefully quell any worries she might have.