I've been following him. He's been to her house, night after night. It was Phyllis and him all along.
7 seconds sound clip from the Double Indemnity movie soundboard.
You can hear this line at 01:28:23 in the DVD version of the movie.
Quote context
[...]
- I guess it sounds crazy, but it was only with her that I could relax and let go a little.
- Why are you crying? Not gonna tell me, huh?
- Of course I will, Walter. I wouldn't tell anybody else but you.
- They killed my father together. He and Phyllis. He helped her do it. I know he did.
- Maybe he was just going with me as a blind. And the night of the murder
- You promised me you weren't gonna talk like this anymore.
- He couldn't show up, because the train was leaving with my father on it.
- Maybe I'm just crazy. Maybe it's all in my mind.
- Sure, it's all in your mind.
- I only wish it were, 'cause I still love him.
[...]