My husband lost his battle with stage 4 leukemia need advise for the kids acting out

We lost him on 10/5/11 75 days after diagnosis, he and I have 2 kids together ages 6 and 8, he had 3 other kids who I have retained custody of ages 14 boy and 15 twin girls, all 5 are having issues and there is acting out to all degrees. I cannot overlook the behavior just because he is gone, yet the older ones seem to think I have committed the worst crime when I take away privledges. I get but my dad died...and such. By the way I am 26 so that is another issue. Thanks for any input