I've had some mean and insulting things thrown my way as well when people see me after not having seen me for awhile. I've been called: underweight, rail-thin, skinny, etc. I'm like: 'shut the heck up because you have no clue what you're talking about' - in my mind, not literally.
As far as I'm concerned as long as my ribs aren't showing, hipbones and collarbone are not sticking out, my face doesn't look gaunt and I don't feel faint or weak, then I'm fine. BTW, my doctor says I'm healthy as a horse, lol.
Only you know the truth. My suggestion is to try to block them out as much as you can. Surround yourself with people that celebrate the new you as opposed to bringing you down.