Damon Dash's not about to give up custody of his daughters to an ex-wife he claims drove drunk with one of the girls, stole diamonds from him, and threatened to cut him with a knife.
Jay Z's ex Roc-a-Fella partner filed docs demanding full custody of 15-year-old Ava and 6-year-old Tallulah -- and laid out some terrifying allegations about the girls' mother Rachel Roy.
In the docs, Dash says Roy threatend his life on several occasions -- once by throwing plates at him, and also by pulling a knife on him. He says sometimes the threats came in front of little Tallulah.
Dash paints a "Mommie Dearest" image of Roy -- saying he witnessed her driving drunk with Tallulah in the car -- and adds he's heard heated arguments between Ava and her mom ... where they call each other "bitch" and get physical.
Roy's also one helluva a jewel thief, according to Dash. In the docs, he says she stole 2 diamond chains -- worth $10k each -- and a suitcase. Not your Samsonite either ... it's a Bottega Veneta worth $5k!
And Dash says he's been blacklisted at Tallulah's fancy L.A. private school, Buckley ... because Roy told the school he's not allowed to see or pick up their daughter.
As we previously reported ... Roy accused Damon of being an unfit Dad for a slew of reasons. She filed for a restraining order, which was granted.