Prom dress help😕😱

Hey sweet girls, I had a perfect dress in the store, red long and tight for only $70 but then I saw this dress and I fell in love with it immediately. I just liked in so much plus it was free. Then I came home, tried it on again and I don't like it anymore and can't see why I liked it so much😢 I'm not skinny but curvy and toned and I feel like in this dress I look fat and not hot😕

It's very important because it's my only prom in my life since I am an exchange student and I want to feel good about myself. What do you guys think?