It sounds like you are becoming a care-taker, even if short term, and that can drain your emotional reserves So Fast. Many people in this situation find support groups useful. Hopefully though, your wife's situation will be resolved soon. I know how disruptive migraines can be to the entire family.
*hug*
You've got to carve out a little time to refresh your spirit, in order to take care of your wife better. You have to love yourself to love her. It's kinda like when you're in an airplane, and the oxygen thingies drop down, they always tell you to put yours on FIRST, then to put it on the person you may be taking care of (child, elderly, incapacitated, whatever). There's a reason for that.