A “Project Runway” castoff slapped his imprisoned ex-lover with a $4 million lawsuit for attacking him with a pot of scalding water on New Year’s Day in 2011, according to a new lawsuit.

Emmett McCarthy, 50, who runs Nolita boutique EMc2 — which hawks $4,500 coats — was sleeping in Pierre Supreme’s Washington Heights pad when Supreme, 46, allegedly threw “boiling water . . . onto the plaintiff’s genital area,” papers filed in Manhattan Supreme Court state.

Supreme pleaded guilty and is serving two years in prison.