Hi S. -
This sounds like classic middle child behavior to me, especially in light our your husband's recent issues and changes in how harsh he disciplines. Look at your daughter's behavior as a sign of stress that needs to be addressed rather than some flaw that needs to be corrected.
A middle kid has to resort to a whole bevy of behaviors in order to be heard and acknowledged. They often feel invisible in the family. The older kids are bigger and better at everything and the younger ones seem to get away with anything. Defiance and anger is a textbook response - not easy to deal with by any means but very normal. It's awfully hard not to notice a screaming tantrum.
I dont know exactly what your husband has been dealing with but encourage him that discipline needs to be reasonable and fair and that harsh is not always best. You are the one who needs to stand up for your kids. If his anger is gets of control, then inform him that it is not acceptable and wont be tolerated especially when it is directed toward the children.
I encourage you all to have a family meeting so that everyone knows what the new rules are and the consequences for breaking the rules so that things are very predictable around your house. Inconsistency is the breeding ground for discontent. I encourage you to make your middle daughter feel like she is very important during this meeting.
You might try a different tack with your daughter when she starts acting out. When she calms down, try getting her to talk about how she is feeling and about the changes going on in your family. Tell her that her behavior is one that a lot of middle kids choose but that it's really hard to deal with and maybe give her some other options to work through her feelings.
I listed some links to articles you might find interesting about middle children.
http://www.lifescript.com/Life/Family/Parenting/Middle-Ch...
http://www.drspock.com/article/0,1510,5547,00.html