Months before he filed for divorce ... the Pregnant Man was attacked by his wife ... who also manhandled their daughter and smashed the family computer ... and he captured it all on tape.
In the footage, expected to be filed as evidence in their bitter divorce battle, Thomas Beatie enters a kids' playroom in his Arizona home ... to find his wife Nancy passed out on the floor.
When Nancy wakes up ... she flies into a rage -- picking up her daughter in a sleeper-hold and dragging her into the next room.
Nancy then inexplicably directs her ire towards Thomas -- attacking him with various household objects ... including the couple's laptop.
Moments later, Nancy takes the computer into the backyard ... smashes it on the ground and tosses it into the pool while Thomas and the kids tearfully plead for her to stop.
TMZ broke the story ... Thomas filed for divorce in February -- claiming Nancy is a violent alcoholic and a danger to their children. Sources close to Thomas tell us he started filming Nancy to show her how she acts when she's intoxicated.
The couple is due back in court on Wednesday to hash out custody and child support arrangements.
We reached out to Nancy for comment -- so far, no response.