Sandy,
I am so, so sorry that you're challenged by your mother's attitude/mental problems. It sounds as if she might have some difficulty with being out of control of the situation, and frustrated by it. I also wonder if she's had some brain damage that is affecting her ability to handle negative feelings.
I would not only tape your conversations with her, but also tape the doctors' visits. That way, if your mother disagrees with you about what the docs say, you can play it back to her. It also gives you a record of what they say for yourself. You should let the docs know that she is uncooperative at home, and is not taking her meds. My FIL plays these games with the docs, too. Acts like the perfect patient, then grumbles at home and doesn't follow orders. It's so frustrating when you are trying to help them as much as possible, and they fight it.
Sandy, you have enough in taking care of Jim. Have you considered an independent living situation for her? They have buses/vans to take her shopping, to doc appts., etc. I worry that in time she will need more care, and you have your hands full already. Some independent facilities have a graduated system with assisted living and full nursing arrangements in the facility.
You are in all of our prayers. I think that calling the docs and letting them know what's going on is for everyones' benefit.
Good luck, and keep us informed...

PS Keep a log of all dr. appts and conversations you have with the docs about your mom.