it sounds like they would have been idiots about anything and that their antics had very very little to do about your weight. Honestly, they would probably act the same to you if you were just 5lbs overweight, or not overweight in the slightest. anything to make someone feel worse than they feel about themselves. I'm glad you walked away instead of giving them what they wanted, it gives YOU the power.
53lbs is awesome!!! I can't wait to get to that point! It's a reality that we will have bad days/weeks, but the important part is to pick yourself right back up. Make a game plan. Have one horrible but delicious meal, but make plans to get to the gym or go play tennis with a friend the very next morning so you can remind yourself what your body truly needs.