Hi! I know this is hard, but -- try not to panic! Take a deep breath and try to relax. I think your outlined plan is the one you should stick with unless something comes up to tell you different. You need the time with your husband since you will not be together much.
Your mom is taking chemo now and starting radiation. That is enough to make her very tired and very sick. I would guess that is the reason she sounds like she does. Is she on pain medication? She should be because bone mets can be very painful. 'As the chemo and radiation work, the pain should lessen.
My wife is Stage IV NSCLC, and has had numerous bone mets. She is 27 months out from diagnosis, so hang in there, and hang onto the hope. Good luck, and keep us posted. Don