Lorenzo Lamas won a big victory in his never-ending war with ex-wife Shauna Sand ... he effectively became the primary parent of their 3 daughters.
A judge radically changed the joint custody arrangement Wednesday from 50/50 to the 3 girls living full-time with Lorenzo, while Shauna gets them every other weekend.
The judge was swayed by declarations filed by the 3 girls -- ages 17, 15 and 13 -- all of whom said they desperately wanted to live with their dad because their mom constantly brought new boyfriends to live with them and verbally abused them, calling them c**** and bitches.
The kids also said their mom rented out their bedrooms and 2 of them ended up sleeping on the sofa and the third slept alone in the guesthouse.
Shauna was sobbing after the ruling came down, but the girls -- all of whom were at the courthouse -- were ecstatic.