Karen,
Don't beat yourself up about "I don't "do it" very well at all. I'm terrible at it." You are dealing with an awesome amount of life changing issues and the fact that you are "dealing" with them certainly proves that you are courageous, devoted, caring, strong and downright amazing! And there are many more adjectives that would appropriately describe the person you are). I can't imagine being in your shoes and I guess the point is that you are doing the very best with all that is being thrown at you. There is no manual written about how to do all you are doing in this situation. I'm glad that you have a place to come and 'vent' when you have to and that you are your MIL are on the same page.
God Bless you and continue to give you strength and comfort.