You in KY? Cause my mom just called tonight to tell me the same thing except it's one case IN my town!! My ds is almost 4. The heeby-jeebies get easier and you do learn to shrug off the uneducated comments. Keep your head up. You will get stronger.
One easy point to look at is that your child could still get many if not all the bugs kids are vaxed for and you might not worry til it was too late because the vaxes should save us all, right? Think how many docs and parents dismiss ear infections, pertussis, even early signs of meningitis because a kid is vaxed.
You will learn, I believe, over time that these diseases have been built into monsters that they most often are not. And will begin to trust your instincts more that you can get through them if they come.
I worried alot more early on. Now as my son is getting older and can help me with his symptoms I feel better. It is good to learn the symptoms of all the common vax preventable diseases just so you can catch them early if you suspect one.
As for your mom, just tell her this decision has been one of soul searching and educating and you need her support not scare tactics. She's your mom, if she wants to love you she should lift you up. Tell her that. ( I know my mom probably thought I was crazy at first, but now she is at least at peace with our choice- she helped us through dd's severe reaction to her first shots years ago so she kind of gets it.) Now when she calls to tell me somebody has a bug it's more like a head's up to boost Vit. C or what not.
It will get easier. Stay here and stay learning. The mommas on this forum have saved my sanity often.