I’m a 67 yr old who brought my 93 yr old mom with dementia to live with me. I feel like I’m getting sick!

Yes, unfortunately by the time you feel sick, you have already been contagious. That's the sneaky, tricky thing about these viruses and other germs.

So, all you can do now is be careful but I personally would not obsess about it because it is pretty much too late. I don't mean that in a bad way. You had no way to know that you were going to get sick and of course would never spread anything to her on purpose. Please do not feel guilty. There is only so much we can do in our own homes. Everyone who lives with someone runs the risk of spreading or getting something from our housemates.

Hopefully you and she will be fine. Eat super healthy, drink plenty of fluids, extra vitamin C, etc. For both of you.

People are letting their fears get the best of them, there is no reason to think that this isn't one of the much more common illnesses that are still circulating. Do what you would normally do to keep germs from spreading -
isolate your mom by limiting her movements as much as possible
clean everything, then reclean everything you touch
bag often handled items like the TV remote (it'll still work just fine)
wear a mask and gloves when you are in necessary close contact with her and when you are prepping her meals

The bad news is that if you feel the onset of symptoms now, you have been contagious for several days already. This applies to most viruses; you generally "shed" virus before symptoms appear as well as after.

Call your doctor. Wash your hands. Wipe down surfaces with bleach or other disinfectants. Make sure mom washes her hands frequently as well.

Also, follow this thread:

https://www.agingcare.com/questions/how-have-caregivers-mentally-prepared-for-outcome-if-we-contract-corona-virus-457263.htm?orderby=recent