As much fun as it will be getting revenge & telling her you are going to buy something vile so that she gets it first & you can have a good laugh at her (that was my immediate reaction
)
I would say that she is clearly at a loss for a style of her own. Like many others have said on here, clearly you are superfantastic & your friend just wants to be too. You should spend a day shopping with her, but only look at things
for her(probably best not to tell her this though) when something looks good, rave about it, saying phrases like 'thats soooo you!' or that dress/top/skirt really flatters your figure & the colour really brings out your skin tone!
You need to give her a bit of a boost of confidence and some gentle instructions on how she should build her own style, without her realising what you're doing.
A really great way to do this is also by picking something & saying 'This is perfect for you, I wish I could wear something like this, but you can really work it' by emphasising that something is fabulous for her, but useless for you, she'll start to get a little feeling of one up manship, which will give her a boost to think that you envy her (in a positive way) & will help to give her the confidence she needs to step out from your fabulous shadow & start to be her own person.
It will be a long process, but you do need to act or the annoyance you feel towards her will just fester in you & get worse the longer this goes on & will end up ruining your friendship altogether.
I hope that makes sense? oh and of course, don't,whatever you do, discuss future purchases you are planning on making or go shopping with her, for things for you!