All the ladies up above have given good advice...

If I were in your shoes, I'd say something like "Screw the 20 pounds... let's lose about 180" and dump the manipulative boy/girlfriend. Nobody that you care about (or who cares about you) deserves to be treated teh way you describe.

Buy the new bike. It'll be better company, take you new places, and maybe change your life for the better. It's a big ocean, and there are a lot of better fish out there in the pond.