I've chosen not to tell my patents or in-laws bc I know they won't be supportive. It's sad, but true. It took me three years to reach this decision and its about saving my own life and living a long time to mother my three, small children.
My husband is nervous, but very supportive, and my best girlfriends are my biggest cheerleaders so I'm VERY lucky to have a great team. But even if I didn't, I made this decision by myself, about myself and would do it anyway.
I hope you will have some peace of mind and that you're family will come around and support you! I bet they're reacting negatively out of fear and worry. Try to educate them as best you can. Good luck to you!!