"I still have to constantly set boundaries, though; they are always testing."

And you always will - and that knowledge must be the foundation of your approach. Would I be right in saying that Any plan which does not factor that in falls flat?

It's hard always anticipating an emotional/psychological ambush, but ultimately it is the most peaceful way.

And you need to set "me" time aside as part of your routine during which you switch off this early warning system which in itself is tiring.

During "me" time, you turn off your mobile and go somewhere fun or relaxing and enjoy your own company or that of your true supportive friends etc.