Eva Marcille's baby daddy, Kevin McCall Jr., went from fighting for child custody to fighting officers and falling down a courthouse escalator ... according to cops who arrested him on the spot.
The drama unfolded Tuesday at the Justice Center Tower in Fulton County, GA ... where McCall was supposed to attend a hearing in his ongoing child custody battle with the "Real Housewives of Atlanta" star.
According to cops, they repeatedly told McCall he's not allowed to record video in the courthouse -- but he had his phone on, and was posting on Instagram Live as he walked through the courthouse. He refused to shut down the feed, and you could see him repeatedly calling a cop a b*tch and telling him to take off his badge and fight.
Cops say McCall swatted away a sergeant's hands, and when backup arrived to detain McCall, cops say he broke loose. They made a second attempt to detain him, and cops say that's when he and the sergeant fell down an escalator.
McCall was booked on 5 charges ... 4 misdemeanors -- obstruction of a law enforcement officer, terroristic threats, disorderly conduct and simple assault. He also earned himself one felony count ... criminal damage to property in the 2nd degree. That might be related to sarge's eyeglasses, which cops say broke in the fall.
As we've reported ... Eva's said McCall's a ticking time bomb, and she's begged the court to block him from getting custody of their 5-year-old daughter, Marley Rae.