caretaking has so many unforeseen challenges for all of us.

there are support groups for caretakers to allow them to vent and to get helpful suggestions from others. these are often free and run by the county you live in.
one thing i feel, imho, is that even tho we are trying to do a good deed, we are not human doormats to be trompled on by our loved ones. being able to say no is important to us to successfully deal with the loved one. i had to finally put my foot down and tell my family member that i was willing to help him but that there was needed certain respectful boundaries in place for us to live in harmony. i was direct what my boundaries are. there are times i do not respond to an argumentative remark because i will not allow him to push my buttons. if he continues i remind him he is overstepping my boundary. if his behavior is inappropiate i call him on it. ii refuse to talk with him unless his behavior is appropiate. it doesn't always work out as well as i would like and that is where the support group comes in. we have to be able to vent outside of our caretaking role. if not, it will leave us heading for depression. anger turned inward can cause depression. i know, it's happened to me. both your stories and my own have different components in it.
i think the most important thing we need to do is take care of our own needs first in order to be able to caretake. not easy i know. secondly, we are not at the total disposal of our loved one.
they need to meet us half way. if they don't then other options must be used...assisted living, etc. many of our loved ones also need support groups to vent. then we are not hearing all the criticism without them learning to problem solve too. it's a mutual compromise we need to find in our individual cases.
this can be successful but the person we caretake's willingness is part of the solution. if they arent' willing to work with us, then it still leaves us with choices that perhpas we'd rather not do..assisted living facility...but we are also entitled to have serenity in our own lives. it is our choice and our duty to self.