The Boy Next Door (2015) online

When a handsome, charming teenager named Noah (Ryan Guzman) moves in next door, newly separated high-school teacher Claire Peterson (Jennifer Lopez) encourages his friendship and engages in a little bit of harmless (or so she thinks) flirtation. Although Noah spends much of the time hanging out with Claire's son, the teen's attraction to her is palpable. One night, Claire gives in to temptation and lets Noah seduce her, but when she tries to end the relationship, he turns violent.