My friends try and make me jealous?

[CLDA]

First of all, this is ridiculous. I'm 22 years old, and I've been friends with this girl, Amy for about 12 years. She's always been a really jealous, negative individual and it's gotten to the point where I can't handle being friends with her anymore so I've basically quit talking to her and really I only speak when I'm spoken to. She has a friend, Stephanie, (I'm also friends with her) and they just moved into a condo together (Amy's brothers condo that he's foreclosing on). Basically, now all they do is try to make me jealous by planning things in front of me, or on facebook, I've actually never seen two people try so hard..point is, they aren't succeeding, I actually don't even care about what they do together. I'm not the jealous type of person, and right now, I'm focussing on my dental school application, DAT, and finishing my undergrad, on top of my two jobs. I don't have time to care. Even if I wasn't busy, I probably still wouldn't care. Amy has always tried to compete with me, but I've made it clear I'm far too busy to care. I told her on Saturday that I couldn't care less, and she said nothing. All her and Stephanie ever do together is spend hundreds of dollars on useless crap..I'd rather save my money. Amy tries desperately to act as someone she isn't, it's sickening. So basically, I want to know how I can make it clear to her that she should stop wasting her breath. I thought about just not responding to her anymore, and I want to know if that's what I should do? I need more of a positive group of friends and friends who are supportive and I don't have that with her.
She wasn't really ever like this, and then all the sudden it changed..so I had no idea she was like this.

Also, don't tell me I care about the stuff she's doing, sure I care that she's going to such lengths to make me jealous, but that doesn't make me jealous, it's just annoying. I have so much more to worry about..