I actually have two that come to mind.

I love the scene from Steel Magnolias when Sally Field is falling apart over her daughter's death. She says, "I just want to hit something!" Olimpia Dukakus grabs Shirley McClain and says, "here, hit weezer!". That one line made me stop crying the second it was said.

I also love the love scene from "Enemy at the gate" It was so perfect and so powerful