“Fatal Defense” (*1/2 out of four) was a fatally dumb thriller about a single mother (Ashley Scott) who signs up for self-defense classes from a young instructor (David Cade) after a break-in at her house but he subsequently develops a frightening obsession with her that soon goes off the rails. Illogical and predictable and often laughably silly. Sherilyn Fenn has a key role as a detective on the case but she would have fared better taking part in the “Twin Peaks” reunion instead of this dreck.