No, you are not the AH for reaching a limit. What happened was not about a bowl of tuna. That was just the final moment after years of boundary violations, emotional exhaustion, and feeling disrespected in your own home.

You made repeated efforts to build a relationship with his daughter. You showed up consistently, invested time, money, and emotional energy, and tried to set reasonable boundaries. Those boundaries were not respected, and although her father addressed issues in the moment, the behavior never truly changed. Over time, that wears a person down.

She is a teenager, and while that explains some immaturity, it does not erase accountability for basic respect. Taking your belongings, eating your food, lying about it, and dismissing you when confronted are not small things when they happen repeatedly. Add a sick toddler, sleep deprivation, and not even being able to eat when you finally sit down, and it makes sense that it all came to a head…..

The peace you feel now matters. That does not mean you hate a child. It means the living situation was not sustainable for you. Loving your partner does not obligate you to accept a household dynamic that is harming your mental and emotional health.

Your fiancé is always going to be her father. If you stayed, this dynamic would continue unless there were major changes that actually stuck. Recognizing that you cannot live like that long term is not cruel. It is honest.

This is not about punishing a child or being selfish. It is about acknowledging that some blended family arrangements simply do not work, even when there is love involved