According to ChatGPT, it might be one of these three -
The Departed (2006), Reservoir Dogs (1992), A History of Violence (2005). Sadly, I don't remember the endings to any of these movies myself so I can't verify! But perhaps one of these will ring a bell.
inappropriatelyitchy t1_ja60blw wrote
Reply to I can't remember a movie name by ferny78
According to ChatGPT, it might be one of these three - The Departed (2006), Reservoir Dogs (1992), A History of Violence (2005). Sadly, I don't remember the endings to any of these movies myself so I can't verify! But perhaps one of these will ring a bell.