Yeah, I pretty much had the ending in my mind ever since the conception of the story. Usually, when I create a new story I always have two things in my mind: the beginning and the ending. I have a rough idea of what's in the middle, but I often prefer creating things as I go.
I finished writing the script for my comic a year ago and, or course, I changed and added many things, but the ending itself is still pretty much the same, just a little more fleshed out.