Almost exactly like The Perfect Teacher (SPOILERS)
http://www.imdb.com/title/tt1663689/
Only differences are, both Gabby's parents are dead in KC and she lives with her sister. And Lucas is WAY older than the teacher in Perfect Teacher.
In both movies, the girl tries everything she can to seduce the instructor and kills the spouse/girlfriend, and tries to get closer to the young daughter. And makes up a sob story about how the guy raped her, when he clearly was the innocent one. Then at the end he tricks her into confessing by pretending to reciprocate her feelings. I saw that coming a mile away. haha.
#pennygetyourownwifi