This isn't going to do you much good now, but if you'd asked me a year and half ago I would have strongly recommended you to begin exercising at the same time you focused on your weight loss. Quite honestly, I'm not sure how you get rid of as much extra skin as you sound like you're talking about. Not my area of expertise. Since one of my favorite sayings is that there isn't any shame in saying "I don't know", I think now would be a good time to live by the rule.
Good luck though.
But I am curious. How exactly did you lose that much weight that fast that it left loose skin? Was it a generally accepted safe way to do it or some "water only" kind of thing?
Rus