Care giver problems

My Father-in-law had open heart surgery and is home now under the care of his wife. They are both in their late 70’s. My Mother-in-law’s mental capabilities are not what they use to be. Memory is an issue, poor problem solving skills, very poor decision making, her maturity level is dropping also, typical of what I have seen in elderly people. She refuses to accept her issues for the most part particularly her diminishing mental abilities. All that being said, since her husband left the hospital, she insists that she can handle all his care including setting up his daily routine, including the large medicine schedule by herself. After just 18 hours there is already an issue with his medication and some of the important instructions given by the physicians. When we asked her about this, all we get is how overwhelmed she is, how she is just trying to get through “right now”, how she did not have time to deal with an upcoming medical procedure and then refusing offered help. She seems to be making herself out as a victim of the demands of his care while again refusing help. She also seems to have a strong need to feel important and she has engaged in obvious and even embarrassing behavior trying to meet that need. I fear that her need to feel important (and caring for her husband alone seems to feed that need) could cause harm or diminish her husband’s recovery process (I will mention again the issue with getting his medication). She made a statement this morning when we questioned her this morning about the medication error she said “I am replacing 9 people from the hospital you know” while refusing offered help. We are at a loss on what we could do to help this situation. I know I have heard of some disorders that sound like this, but I don’t remember.