When I give KR the benefit of the doubt that she was totally in the dark, this is the scenario I envision.
If she truly had no foreknowledge of her husband's terrorist plans, she's probably distraught about Officer Collier's death, as well as feeling anguish about her husband's & brother in-law's bombing victims.
If she had no foreknowledge, she may regret that she hadn't contacted LE, instead of Tamerlan, when she saw his face on the news.
I find it interesting that no one has claimed Tamerlan's body. As his wife, she would have the primary legal right to do so. The fact that she hasn't done so tells me that, at this point, she wants nothing to do with him or the disposition of his remains.
Personally, I hope no one claims his remains. I hope he ends up cremated & disposed of in a common grave, which is allowed under MA law.
http://www.malegislature.gov/Laws/GeneralLaws/PartI/TitleXVI/Chapter114/Section43m