I'm so so pissed my mil crossed the line we are my husband's grandma's caregivers and my mil knows that her mother isn't…

I'm so so pissed my mil crossed the line we are my husband's grandma's caregivers and my mil knows that her mother isn't supposed to get upset so what does she do she comes over when my husband and I are out and starts shit with her mother then leaves right before we get home so we get here and his grandma is crying so hard she starts hyperventilating that bitch went way to far she will never see my kids again