Dar, I would get her into counseling if she is saying she wants to do harm to herself. That's a cry for help for sure.
I think some of the attitude they pick up they learn from school.
Then I also think my S7 thinks he can disrespect me because his father does. He probably figures if his father does it why can't I?
This is why I have sat s7 down and told him that the way his father talks to me sometimes is just not right. I told him I don't deserved to be treated that way.