I had a lot of problems with this too. Close family and friends, I made sure that they knew everything that was going on. I asked them to not speak publicly to their friends or family, and I just wanted to make sure I had a strong support system before I went into having WLS.
After the first few months of dropping weight, people obviously started to ask questions but at that point I was comfortable enough to explain what I did. I thought I would have to explain my reasons or argue with people, but honestly they could see how much happier and healthier I was. After loosing 200 pounds, most people don't really ask how I lost the weight, if they haven't seen me..all they can say is "WOW YOU LOOK GREAT CONGRATS!"
It's a personal choice, whatever YOU feel more comfortable doing.