Oksana Grigorieva claims she suffered from "battered wife" syndrome -- at the hands of Mel Gibson --  and that's why she was so slow on the uptake to blow the whistle ... sources connected with Oksana tell TMZ.



Sources close to Oksana tell us right after the alleged Jan. 6 attack, Oksana broke off her relationship with Mel for about 3 weeks.

But then she went back ... and was overtly affectionate with Mel in various ways.  Oksana is telling friends, Mel tearfully convinced her the alleged attack was a one-time-only incident and that he would go into therapy to get better. 

And there's this ... sources connected with Oksana now tell TMZ ... her "close" relationship with her bodyguard -- Kristian Otto Herzog -- is further evidence she's drawn to men who have violent tendencies.

But there's more with Mel ... Oksana says she was a closet girlfriend until the January 6 incident. Then afterwards, Mel promised he'd treat her like a trophy girlfriend, taking her out in public -- like the Golden Globe event -- and publicly bragging about their relationship.