Kate Major is staring down the barrel of some SERIOUS jail time -- TMZ has learned Michael Lohan's ex-GF has been charged with battery for allegedly attacking 3 people on a boozy tirade in Florida.
TMZ broke the story ... Major was arrested on January 14th for allegedly beating up a Latino couple in a parking lot ... berating them with racist epithets ... and then calling the arresting officer a "fat f**k.
Major has been charged with 3 counts of battery, 1 count of resisting arrest and 1 count of disorderly intoxication ... all misdemeanors
If convicted on all counts, Major could face more than 4 years behind bars.