As awful as this experience seems it can be a real and fortunate wakeup call. The circles you were/are inhabiting are cutthroat status and wealth competitions and very much zero sum contests as well. If a little added weight reduced your looks granted status then somebody else's status could rise, and in all probability some of the cruelty directed at you was intended to stamp in this new ranking, as well as to show resentment for your former ability to rise in esteem using an avenue closed to them.

Everything you can gain by looks can be just as easily taken away, the "friends", the perks, the attention, all are ephemeral. You know this NOW, not ten or fifteen years from now. Your options to build relationships and accomplishments based on real connections and real excellence are open to you NOW, and if you need a fire built under you to seek this authentic status and success all you need to do is remember the creeps who turned on you so quickly when they could.

I say this as a person whose physical expression in the world gained me nothing and cost me much dismissal and some ridicule. I know with a certainty that those who desire my company, my skills and talents, my empathy and emotional support do so ONLY because they see the authenticity in them, and NEVER to gain status or regard by being seen with me. That's not always fun, it would have been great to have some people attracted to me physically, but knowing that there is no change I can make in my body that will change my attractiveness is freeing. Go for the real stuff...good luck!