As Someone with a small dick, and fat on top of that, believe me when I say noone worth listening to actually cares. Don't feel like you need to prove shit to anyone, when someone tries to make fun, turn it on them like "well I'm not the one looking at pictures of dicks, it's ok to admit if you got a kink bro" etc.

Turn it, marginalise it, ignore it. If you are hurting don't show it to these people, they thrive of your pain. If they share the pictures report it to the police because that is essential sexual harassment and it's illegal. Those dudes sound like they could use a reality dose.