It sounds like the relationship is a huge source of stress in your life. I don't think you should do anything at the expense of your well-being when it makes you feel like you are being pushed over the brink.

In terms of dealing with her, have you told her flat out that she doesn't have all the answers and that it doesn't work that way? And that ultimatums are inappropriate? And that all this pressure just makes you feel worse, to the point that you dread going back home?