I only remember probably the final part of this movie I saw on TV a long time ago
The scene shows a woman in night gown drinking a glass of wine while enjoying some music (not sure) at night. A young boy was peeking out from behind either his room or his parents’ bedroom. Suddenly, both parents (assuming they were his parents) were in severe stomach pain. It was clear the boy had poisoned their drinks. They tried to attacked him. The boy eventually brought his mother downstairs as she tried to attack him. He placed her on a chair as she moaned, slowly dying from the poison as he watched he. Suddenly, the father attacked the boy from behind in a final effort to kill him but failed. Both parents eventually died.
The last part shows a middle-aged man (probably the boy grow up) telling another person the story. I believe the movie maybe his story but I’m not sure.
This is all I saw when I came across it on TV.