"Blood, Sweat & Heels" star Geneva Thomas is suing her co-star for $25 MILLION ... claiming the woman got her falsely painted as a violent criminal.
Thomas claims Melyssa Ford defamed her after an ugly fight on a boat last week while shooting their show. Ford claimed Thomas grabbed a glass bottle and shattered it over her head. Ford had to get 3 staples in her head to close the bloody gash.
We have video of the fight -- it's not clear who started it and we don't see the bottle smash ... but Thomas is pretty confident she's in the clear.
Apparently authorities disagree ... Thomas was arrested after the fight and she's been charged with assault and criminal possession of a weapon.