How to cope with jealousy?

I get so jealous when my girlfriend talks to all her ex's or people she has be sexual with. I know she will not cheat on me, but i still get incredibly jealous. I also get jealous when she says that celebs are hot and how she says she would have sex with them if she could. I feel like im nothing when she says that, and that im not pretty. Ive told her i get jealous but she still does it. I have NEVer been jealous of this stuff before. So why am i jealous now? How can I change it?How to cope with jealousy?
hmmm...maybe u get jealous cus u really like her. try to do a little bit of what she does. (but not to much) see if i gets her jealous then use it as an example. if that doesnt work then maybe shes not the one for you