Practicing mindfulness in a parasitic system actually trains that system to exploit you even more. /1
Here is the exact mechanics of how your calm state acts as an invitation for others to dump their burdens onto your shoulders, destroying both your health and your situation
The Game Theory of "Calmness" (The Parasitic Feedback Loop)
In a family, and every other sentient beings system, everyone is trying to minimize their own free energy (stress, effort, and unpredictability) [Friston, 2010]. Let's say, you yell from exhaustion. This way you are sending a massive, high-precision sensory signal to your family. You are setting a boundary through raw emotion. That yelling increases their free energy by making them uncomfortable, creating unpredictability for them, and signals that if they push you any further, the system will explode. Out of self-preservation, they might step back or take on a task just to quiet the storm.
What happens when you practice mindfulness and acceptance instead. You artificially lower your internal distress. You become calmer, quieter, and more compliant on the outside.
The Toxic Result is that your family members non-verbally and unconsciously detect this. To their brains, your calmness signals, "The boundary is gone. The danger of her exploding has passed. She has more capacity." Because human beings naturally seek the path of least resistance to save their own energy, they immediately shirk their responsibilities and offload them onto you. Your "zen" becomes their green light to exploit you.
Mindfulness as a "Balm for Sore Fingers" While the Bones are Breaking
Using mindfulness to cope with an uneven distribution of labor and emotional neglect is like putting a band-aid on a broken finger so you can keep swinging a heavy hammer. It changes your perception of the exhaustion for an hour, but it does absolutely nothing to change the physical reality of the workload. Tomorrow, you wake up with the same broken bones, but now you have to lift an even heavier weight because your family realized you wouldn't fight back.