Triangle
(2009)

Short Version:
Jess remains stuck in her triangle time loop

Long Version:
Jess (Melissa George) ends up being knocked overboard by her double and winds up back on the beach, she makes her way home where she encounters her past self abusing her son. She proceeds to murder her past self with a hammer then drive off with her son only to be involved in a fatal car crash. Suddenly Jess is standing on the road before making her way down to the docks, where upon the time loop begins again.

Thanks N.D. Woods!