My friend likes my boyfriend?

so there's this guy that I have liked for 3 years now and he finally asked me out about a month ago. the thing is i have a friend that likes him too. she doesn't know that i know she likes him, so its kind of awkward around her. also shes not the greatest friend, she acts like your best friends when your with her but the second you leave her alone she goes and gossips about you. also i never find her without my boyfriend, sure ill see him without her but never her without him. she is all over him. for example; our class went to the beach for a trip and one of my good friends squirted sunscreen all over his back, she automatically comes up and starts rubbing the sunscreen in, isn't that my job? my boyfriends a really nice guy and i don't think he has picked up on the fact that she is head over heels for him, and i dont want to be rude because they are kind of friends already, is this just a bad case of jealousy???? I DONT KNOW WHAT TO DO :(