Brooke Mueller -- Assistant Claims He Was a 'Drug Mule'

Brooke Mueller's former assistant has filed a lawsuit against her ... claiming she turned him into a "drug mule" to fuel her out-of-control habit.

Lior Masaphor wants her to pay unpaid wages, but he makes claims going way beyond that. He says he was forced to watch her twins Max and Bob while she got "so high as to be literally wasted" and engage in multiple sex acts with other people while the kids watched.