Not trying to be a dick here, but she's had plenty of time to mourn her father and brother's deaths. She's 21 years old now. Her father died when she was still in Junior High (aged 13 or 14) and her brother a couple of years later. I'm sorry, but if you think she's using that as an excuse for her behaviour, it's unrealistic not to mention unbelieveable.
Did she have a bad day? Maybe. But you'll be lucky to find people who'd accept deaths in the family from 6 or 7 years ago to be an acceptable excuse. It also still doesn't excuse her lack of professionalism, which she herself admitted to. She's an actress who's in the public eye. Regardless of what she's going through in her public life, she has commitments to fulfill and the show must go on.