"Wow, the more she's fat wearing a bikini or lingerie, doesn't she realize she's ugly?". No! It's not ugly, it's beautiful, or rather: they are beautiful. Lose weight? Only if it's for health reasons. If your weight doesn't bring you any kind of health-related problems, don't lose weight just to fit society's standards.
Don't hide from the mirror, beauty is not measured by clothing sizes, look at yourself with your eyes and not with the eyes of prejudice, or rather, of the prejudiced. Be the first to love yourself, because when self-love comes into play, there is no opinion that makes you feel less than you are.
If you look in the full-length mirror, go back to wearing those colorful clothes that you had abandoned to make way for the little black dress, the one you were told to wear because it apparently loses weight. Put on that bikini or lingerie that you no longer wear or want to wear so much, but you don't because you've been told that it looks ugly on you or that it only suits thin women.
Go out dancing, yes, have fun, even if they say "how ugly that chubby girl dancing", and even if they say "there's nothing that looks good on her", "it's no use wearing makeup because she'll always be ugly, she's fat", you is beautiful!! Yes it is beautiful! You look diva in that piece you love so much, yes, you look sexy in that lingerie you love to wear.
Hey babe, measurements are not a parameter of beauty! Use and abuse that piece you like so much, other people's prejudice doesn't fit you!