Under the "not really a horror movie, but it scared the pants off me variety" -- At Close Range with Sean Penn and Christopher Walken. Based on a true story, it's about a criminal lowlife father (Walken) who has his sons killed to avoid having them testify against him to a grand jury. Walken was at his absolutely sociopathic, evil best!
When Walken is telling Penn "what.. you wanna hear me say i love you? i love you"... and in response Penn fires a round at Walken... classic facial expression there..
ping obscure but good movie reference