I was just wondering what the proper way of writing someone's dialogue is when they are being cut off in speech. Do you use a quotation at the end or just leave it hanging with the dash?

Ex.

"Stop it! What the hell are you--"
"Stop moving, damn it. You're going to rip it."

Or is it,

"Stop it! What the hell are you--
"Stop moving, damn it. Your going to rip it."

Okay, for some reason the dashes are not showing up here as one longer dash the way they do in my MS, but you get my drift. What is the proper way of doing this? When I put the end quote on one of my sentences where there's speech being cut off, the quote comes up backwards. Am I making sense? Do you kwim? Thanks for your help.

Mel