what are antigene's justifications for her actions?

The answer to this question is very similar to your first. Antigone justifies the burial of her brother as commanded by the gods. In a very religious world, she takes her beliefs seriously.... human law is not above the law of the gods.... she justifies her actions as being her only choice, and in her world, it was her only choice. To obey the laws of man at the expense of the laws of the gods would have been an unforgivable mark upon her..... she obeyed the gods and believed they would sanction her actions.