@purplerain101
Oh FFS what a nasty horrible thing to happen - and you are NOT over-reacting and have every right to be upset and hurt. And this 'friend' is a behaving like a fucking cow.
OK here is my twopennyworth!
You say she put 'some people make a mountain out of a molehill,' and people 'liked' it - but these people may not have known what she was on about. I sometimes 'like' posts on FB without paying attention. (I usually do but occasionally don't!) So don't assume everyone is against you. (I know that's easier said than done when you are hurting...)
ALSO, you doing the 'blocking' and moving away from it, has given the woman a perfect opportunity to get her side firmly across. Do these other friends know what was said and what she did?!!!
You need to get your side in. Unblock, and go onto the group chat or FB thread. and post 'you KNOW what you said, you backstabbing nasty cow. You mocked and laughed at my dress sense, and then when I got a bit upset about it, as I was ENTITLED TO - you told me to not be so sensitive and shut me down, like I was a fucking snowflake. And now you bitch about me behind my back to others. Unless you apologise, you are officially out of my life! And so is anyone else who sides with you! I am worth better than this fucking shitty treatment!'
Make sure EVERYONE knows what she did and how she treated you!
(You may wanna leave the bad language out - it's up to you!)
And then leave others to make up their mind. It's a tough thing to do, but don't leave it like this, as SHE is winning when SHE is in the fucking wrong! 
You poor soul, you sound so lovely, and your dress sense DOES sound great. (I love boho style) I am gonna agree with the posters who say she is flat out jealous of you.
What a c*nt she sounds.
But yeah, don't leave it. Get your side in. Talk to these friends and tell them what she said and did to you. How DARE she treat you this way? What a fucking cow!
Upshot is - don't assume everyone has turned against you (though it's easy to think this at the moment!) because I think all people are doing is listening to what she is saying and hearing her side. The 'silence' from people is probably coz they don't know what to say, or are waiting to hear from you...
You need to get your side in and let people know what a bitch she is. And maybe try and find out which friend she was sending the message to!
Good luck. I hope you get this sorted. She owes you a massive apology. Online AND in person.