Sugar Bear -- I Didn't Cheat on Mama June!

Sugar Bear is standing up for himself in the break up with Mama June ... insisting he has not been online dating and has NOT cheated.

As TMZ first reported, Mama June kicked Sugar Bear to the curb after finding out he has a profile on the dating site plentyoffish.com

This weekend in Georgia ... Suge was asked about his online dating adventures and stood up for himself. He's tight-lipped on details, but adamant he's not a cheater.

He also says he's "not allowed" to talk. Question is ... who's trying to muzzle him -- producers or June?