What a fantastic achievement. Maintaining your weight is where the work really starts... 
This time next year you'll think losing weight was actually the easy part!
Hopefully, after spending a long time losing the weight you'll have got into a good routine of eating more healthily, controlling portions better, controlling 'treats', managing nights out/holidays etc., and doing some daily exercise. You only have to increase what you eat slightly and there you go - you're maintaining. Keep weighing yourself about once a week. If you gain more than 2 or 3 lbs, trim back on the portions again or up the exercise until things stabilise. Count the calories occasionally as a spot check.
When I lost weight I heard some statistic about how 80 or 90% of successful dieters regain all the weight lost within 18 months. And I swore then to be in the minority and buck the trend!!! I think it helped me, it might help you.
A big steak and a brownie sounds lovely.
I reached my goal weight last year in October, I lost over 60 lbs. I know what you mean about the "failure" feeling when you step on the scales--over the past year I've gradually lost 10 more pounds. I still feel great and I'm starting to think I'll never be overweight again, but maintaining is really hard mentally. I think gi-jane is right about bucking the trend--it's just going to be a life time challenge to find the right balance. I think of it almost like a hobby now and that seems to help. Best of luck to you!
