@whutchison I didn't do the clean up, but I was right by my husband when we found the first droppings. They were in a ceiling light fixture that wasn't working, so we took off the light fixture and then found the poop. So I was there when it was disturbed. My husband would then clean everything by spraying with bleach while I stayed upstairs. We eventually put down poison in the walls (which I worried about, too), and I was there when the mouse/rat/whatever it was took the poison - could clearly hear the scratching a foot or so away from me. So I was definitely in the vicinity of the animal(s) and the poop, and never with a mask. They were actually in our house too - in our kitchen. So more exposure than in the garage.
As mentioned I had also been drinking tea, and a week or so after we found the mice I decided to look into the kettle and yep, mouse poop. I still feel sick thinking about it. But neither my baby or I seem to be any worse for wear.
We did eventually get rid of them (I think), but we moved before the next cold season for other reasons, so I have no idea if they ever came back.
I completely empathize with your anxiety. Would it help to ask your doctor for a blood test? If it's LCMV you're worried about, you can take a blood test a month or so after exposure (the wait is terrible). It's worth noting though that congenital LCMV is VERY VERY rare, as is hantavirus. It's good to be aware and careful but the odds are very much on your side. And again - I can't imagine it getting worse than drinking mouse poop tea and my son is beautiful and so far, there is nothing to indicate that he isn't healthy.
With me, eventually the LCMV worry was replaced with a new worry - classic anxiety. It's a struggle because while you aren't technically wrong - mouse droppings CAN be an issue (as can every other thing I worry about) - the odds are very much that your kid will be fine. Kids (and people) encounter toxins/"baddies" all the time and are extremely resilient. Moreover, I feel confident that you can handle whatever is thrown at you - you're clearly a diligent and caring mother, and whatever happens with your kid, you will love them and give them your best. (Though truly I think your baby will be 100% fine).
I eventually reached out to a therapist, because in my case, I'm very aware that I will never be able to protect my kid 100% and my anxiety sometimes gets in the way of being a present mom. I want to let him live and not grow up feeling scared, like there is danger lurking behind every corner. This may not be your situation but it certainly is mine, and I'm always happy to chat more if you're in the same boat (and sorry for the novel! My heart just goes out to you).