clothing help!

I just got to work. My leather jacket has a heavy-duty zipper, which at the moment won't unzip past the bottom. I can't get it off over my head. Any suggestions for twiddling the zipper so I can get it working again?

Key fact: the cloth bottom edge of the two sides is not lined up -- off by one tooth-width. On close examination, it looks like the teeth are supposed to start RLRLR... (my R and L), and instead started LRLRL..., with an unused gap between the first L and the long metal starter on that side (where the first R was supposed to go).

That's where the zipper stops. I don't want to destroy the zipper on my jacket... nor do I want to spend all day with it on! Help?

[Edit: I got it off over my head. Also, the square bit that both sides go into at the bottom popped off. However the zipper is still stuck.]

Jacket outcome

Dropped off leather jacket at tailor next door to Diesel. She took one look at the zipper and said "Have to replace it. That's a heavy-duty zipper. Forty-five dollars."

I forked over the money. Thanks very much pinkfish for advising me not to muck about with trying to repair the existing zipper.