While you can't "spot reduce", you do need to watch what you eat and a diet that is generally "good for you" will also help you get rid of your belly.
You need a balanced mix of lean protein, low/no fat dairy, fruits, veggies, whole grains, "good" fats, etc..........
I'd recommend that you try a food diary - med help has a great one - in which you log everything you eat - even the "bad" stuff ---- that will help you see exactly how you are doing food wise; whether you are eating too many carbs, too much fat, not enough protein, etc.........
And of course - exercise. It takes a variety of exercise to tone and firm all your muscles, so don't just stick with the same routine every day. Make sure you mix it all up -- weight bearing, aerobics, etc.....
It's very unlikely that you've damaged your body for good..........
A lot of belly fat is related to Visceral Fat. There is a good article from Calorie Count about this.
http://caloriecount.about.com/visceral-fat-b337280?utm_source=newsletter&utm_medium=email&utm_campaign=newsletter_20090924&utm_term=continue1