Spanx tank are wonderful things!
Also, I have found that there are some great books out there for dressing your body shape, whatever it is. I tend to carry weight in the middle but even at my weight, there are ways to minimize how that looks.
Have you had children? Or been very overweight? Because either one can cause your abs to separate in the middle and that can cause a poochy stomach to varying degrees (from not so bad to requiring surgery). Most people who have had a baby have some degree of separation. There are specific exercise you can do to fix that.
I hope you manage to have fun anyway and I'm sorry your mom's "friends" were so mean.