"People think kids act like this just to piss you off and they don't"
Not true. If it was a 2 year old, then, yes, maybe the child is doing all the wrong stuff because she doesn't know better. But at the age of 8 most if not all of that behaviour can be quite deliberate; and in this case I think it is deliberate. She knows very well what kind of effect her actions have. Children are way smarter then we think.
Remember - the child spends considerable amount of time with her mother who is a suicidal person suffering from bipolar disorder, and who is certainly using her time with her daughter to turn her against her dad and his new wife.