我想你應該是想問英文該怎麼說吧.

You freaked me out.

另外一個我覺得不錯可以分享的(電影裡聽到的)：
You take my breath away
不完全一樣,但是很生動的

interesting topic: Maybe not quite suitable for your example, but is "scare the bejesus out of sb." one ? :)

I think the best and most direct translation is: 'you scared me to death!' As below:
吓死我了，我还以为我说错话了呢。 You scared me to death, I thought I said something wrong!!
吓死我了，你以后别突然在后面拍我 You scared me to death, next time dont surprise me from behind!!

What Linda said souds OK for this:
你个死变态 you freak!
你白痴吧你 you idiot!