Durst ‘attack’ before slay

Real-estate heir Robert Durst attacked one of his friends without warning before his wife disappeared — viciously kicking him in the face with a pointed cowboy boot — in what prosecutors described as a precursor to her presumed murder.

The unprovoked assault came to light Monday during the pretrial testimony of Peter Schwartz, the alleged victim.

Los Angeles prosecutors called the Connecticut therapist to the stand in hopes of tying the violent incident to the unsolved disappearance of Durst’s wife, Kathy, who went missing in 1982.

Schwartz claimed it was January 1981 when the attack went down at a party in Manhattan.

He testified that after the assault, Kathy told him and the others who were at the party that Durst owned a gun and wasn’t afraid to use it.

Prosecutors later told the judge that they believed Kathy went home that day and got into an argument with Durst over the incident, right before he presumably killed her.