Despite the possible stress, rely on your family
The odds are likely that your family is going through many of the same struggles that you are when it comes to caring for that person, so it is important that you all be open and honest with each other.
Sometimes, this can be difficult, as certain caregivers will inevitably feel as if they are doing more than another family member, and feel a sense of injustice. However, instead of letting these feelings fester, it is important to get them out in the open.
Some people might not be doing as much as you are, but instead of what might be going through your mind about them (that maybe they're selfish or lazy), it could just be that they have not been able to find a way to help. So, ask them to assist with things you need done, and they will likely help you out.
While you might be reluctant to follow some of these strategies, in the end it will be best for both you and the patient. Your job is hard, so make it the least stressful it can be.