The bloody brawl Bobby Brown's family had last Thursday was blown way out of proportion ... says Bobby's nephew who was hit with a glass, but insists he'd never call his mom a "crackhead."

Shayne Brown tells TMZ he's got nothin' but love for his mom Tina Brown -- the two sat side by side at the vigil for Bobbi Kristina Monday night ... he claims she'd been drinking, and was upset a random friend crashed the family get-together at the W Hotel in Atlanta.

He says he was merely in the wrong place at the wrong time when she chucked the glass that struck him in the head ... later requiring 5 stitches. 

Shayne insists the only tension in the family are the high emotions swirling around Bobbi Kristina.