Sorry, I think that is a crappy excuse. We all have some kind of stress in our lives, but that does not give us the right nor is it okay to do whatever we wish.
SHe might be dealing with a lot right now, but grow the fuck up and act like an adult. Just because you were dealt a shitty lot does not mean you now have the right to treat others with disrespect.
You reep what you sow.