The title says it all. But i'll describe further.
You are playing The Sacrifice in Left 4 Dead 2. You are playing realism mode on the expert level. You hope to get the Real Deal achievement, which involves "surviving a campaign on expert difficulty with realism mode enabled."
You sacrifice yourself (as someone has to) to complete the campaign.
Do you get "The Real Deal"?
Best Answer
No. Well, that shouldn't come as a surprise, since you don't exactly fulfill the "surviving" part.
It's your funeral, so, you're an acceptable casualty :)