Pardon Me While I Panic

My husband's family is going through a bit of a crisis right now and, being pregnant, my brain decided it would be a great idea to go into selfish-panic mode. Before I whine explain, let me lay down the facts:

1. Steven's (retired) paternal grandparents have offered us free childcare once the baby arrives, which we gladly accepted.
2. His paternal great-grandmother is showing signs of dementia and is now moving in with his paternal grandparents.
3. Great-grandmother has been known to have a mean streak which is only exacerbated by the dementia.
4. Great-grandmother has shingles.
5. I (the pregnant one) have never had chicken pox, but I was vaccinated at age 13. However, I have since never been around anyone infected with the chicken pox so I don't exactly have proof that the vaccine was effective.

The short term panic is this - I am terrified to go near Great-Grandmother or go in any home she has been in. I have heard the chicken pox / shingles virus is highly contagious and might be airborne. So it only makes sense not to touch anything she has touched until I get the OK from my doctor. Same goes for Steven. I can't have him hugging her then hugging me, thus transferring the virus to me and my unsuspecting baby.

The long term panic is this - I am terrified to leave my baby in the same house as someone who doesn't have full grasp of their mind. Yes, there will be other adults present and she will never be alone with the baby, but I still can't help but recall horror stories of dementia patients doing unintentionally destructive things.

I am fully aware that I am a selfish, horrible person for worrying over hypothetical problems when there are real problems at hand. Please explain that to my hormone addled, panic-prone brain. I also have faith that my family will make all the right decisions and not do anything that will put me, the baby or anyone else in harm's way. It is very possible that Great-Grandmother will regain some mental clarity once someone else is managing her medications and she is getting the care she needs. Also, I am aware the baby won't be here for another 24 weeks and won't need childcare for several weeks after that. I am confident that all the kinks in our family's system will be more than ironed out be then.

But seriously, all the logic in the world can't stop me from worrying right now. Please tell me the worrying gets easier. Oh, it only gets worse? Well then, I'm screwed.