I'm so sorry to hear that you are going through this.
Unfortunately you are going through one of the most difficult times that a person will ever have to go through in life - and I really think you need to cut yourself some slack.
As far as your eating and the carbs go just try to make better choices. Try not to go overboard with portions. Because even if your choices aren't the greatest, and quite frankly that''s to be expected, at least you can try and keep the portion sizes in check.
Exercise is a great time to "steal" some time away from all the chaos. Maybe for the time being you can find 20 or 30 mins in the early morning and/or 20 or 30 minutes in the evening to so something light. Either a nice quiet brisk walk or a bicycle ride. You just may find this very theraputic.
For the time being, whatever will be - will be - and you know what? It's more then good enough. It has to be, that's just the way things are sometimes.
I wish you, your mom and your entire family all the best during this excruciatingly painful time.