Mom, if you have bronchitis, I assume you are coughing a lot and I don't see how you can cough and wear a mask at the same time. Sitting up should help the coughing as well as the apneas. Are you taking anything for the cough?
If it were me, I would leave off the mask until I stopped coughing, or at least until I could control the coughing with some kind of cough medicine.
Actually, if it were me, I would try to find something more comfortable than sleeping in a chair. It did happen to me a couple of years ago and I piled up the pillows so that I was nearly upright and put a down (or feather) pillow behind my head with the edges tucked over my shoulders to hold my head from falling sideways.
Bronchitis is miserable and my doctor told me that the coughs are slow to clear up. Do the best you can and eventually it will all go away. In the meantime, lots of commiseration, which is no help at all!