ESH (except the dog)

I don’t believe you meant to hurt the dog, but I find it hard to believe that there was not another room you could have put the dog into, which would be just as easy as putting him/her outside. Or you could have left, put the dog in the crate yourself, gone to a room/bathroom away from the dog and called your sister, etc

But instead, you made a poorly thought out and irresponsible decision which endangered the dog- who could be hit by a car, taken to a shelter and euthanized (pit bulls are at a high risk for this), contract a disease like parvo, etc. not to mention the emotional distress your sister is probably in right now- and you NEED to take responsibility for your actions

Also, I work with animals and I’m not sure what you’re describing is an ‘aggressive’ dog-to me it sounds like an over-exited and untrained dog . I guess you could have described his/her actions poorly, but I doubt your sister would leave you alone with an actually aggressive dog.

that being said, your sister should not have left you alone with an untrained animal who has the capacity to harm your child, especially if you expressed you were uncomfortable. I would also recommend you talking to your sister about training her dog better, as pitbulls face lots of discrimination and can’t get away with bad training like a lab or Yorkie might.