'Game of Thrones' Star Jason Momoa -- My Wife's Suing Because Other Driver TOTALED Our Car

"Cosby Show" star Lisa Bonet's Audi was totaled in the 2011 car accident she's now suing over -- so says her "Game of Thrones" husband Jason Momoa ... who tells TMZ, the family's now on a quest for JUSTICE in court.

Jason was out in L.A. yesterday with his mom (HAPPY ALMOST MOTHER'S DAY) when we asked about the accident ... and Jason told us just how serious it really was.

TMZ broke the story ... Lisa just filed the suit claiming she and the couple's two young children -- aged 4 and 5 -- were badly injured in the accident two years ago ... and the other driver should pay.

Jason says his family's recovering well ... but they're really lucky to be alive ... because the damage to their car was irreparable.