You need to put up a boundary for yourself and know that your family will continue to try to push that boundary. You just have to stick to it like a broken record, no matter how much they try to push your boundaries. They will push because they want to see if you mean it.

On a side note, I have felt triggered many times while parenting and found meds, counseling, CBT and parenting skills helped with coping. It can be very challenging to look after children.