I agree with the other posters, ultimately this decisions is yours alone to make, and you are doing it for your health. It sounds like you have a good head on your shoulders about the decision, and I can relate to being frustrated when others just don't "get it".
I'm sure what you're experiencing is not only jealousy, but pure concern on the behalf of some. Many people don't know a lot about this surgery, and may assume it's just as risky as gastric bypass, or something else that's more invasive.
I say tell your friends when you feel it's the right time for you (when, or if, that time comes). When you do talk to them, just explain you are doing this for yourself, your health, and your children. Afterwards, I say just leave it at that. If they have real questions about procedure fine, but if they want to "bash" or minimize your choice or efforts then change the subject or ignore the response as best as you can. Your real friends will sort themselves out I'm sure...
Best of luck to you!