All she was yelling about really could have been spoken in soft, concerned tones. She could have expressed her worries, her needs, her wanting to comfort him and just be with him, in a completely different way. Her yelling at him was just a release of the anger she had towards everyone else in their house. The blame had to be put somewhere. Seeing as he'd taken over frightening the elves, and yelling at her sister wasn't an option (for she still felt very much in debt to her sister for keeping her secret), Lucius was all she had left.
"Do not speak down to me, Lucius Malfoy," she snapped right back. "I am not a house elf you can berate and disrespect. You have no idea what it was like. I realize you were in no better place, but do not stand there and assume that we were living the high life in your absence. I did what I had to for Draco, and you're right. Perhaps I should do it again."