Should I use 就 in when translating "when you say it like that, I feel confused", e.g. ...我就感到困惑?
In short:

你这么说的时候，我就感到困惑.
Whenever you say it like that, I feel confused.

你这么说的时候，我(会)感到困惑.
When you say it like that, I feel confused.