Nick Cassavetes is the embodiment of evil who has waged a campaign of revenge against his ex-wife for leaving him ... this according to the ex-wife's mother.
Linda Massad tells TMZ the famed director has scared her family so much they have gone into hiding. She tearfully described the scene at her house where strange people have been showing up ... she's worried someone has put out a hit, but she offered no evidence to support the claim.
Linda does say "The Notebook" director strong-armed her daughter, Heather Wahlquist, into giving Nick certain custody rights over 13-year-old daughter Barbie, and says she's worried sick he's going to take their child and run.
We reached out to Nick for comment ... so far, no word back.