May I jump in here? I've twice been a step mom...the first time was the real shocker for me...I met my step-son with his father after school...we went to Bury St. Edmunds for dinner...his son ended up screaming and crying (he was 12) and would not even walk on the same side of the street with me. That should have been my first clue that things weren't going to get easier. He made his father take him home and after his father and I married, the visitations were horrible. In the end my step-son did everything he could to cause problems...it was his way of letting me know that he would never accept me in any compacity, no matter how nice I was to him.
He was angry with his parents for splitting up only he could not show anger to them...so it was me who got all the resentment/anger reactions.
My second time around is now...with grown step-children...fortunately, my husband has stood by my side and not let his grown step-children push me or him around. They've tried some low shots but refuse to take responsiblity for their inappropriate actions...Larry and I have stood side by side and have not let them damage our marriage. If he had not taken the stance he did with me we would probably be in serious trouble.
Bottom line here: Your husband needs to take his snotty little kid (raging hormones and all) and tell her she either straightens up and behaves or is out the door to her mother's house permanently. Second, she needs to be in counseling...I was a step-child myself from a very young age and issues I had back then were never addressed...the loss, pain, etc., and they have affected my life up until even now...all of you are affected by this and all of you need some kind of counselling to cope...you and your husband need marriage counsellling to reconnect priorities...he must stand by you and stand up to her.
If it were me and my husband did not stand by me and expected me to deal with this alone, he'd find himself alone with his out-of-control daughter. Maybe I'm too cold hearted, but it's not worth it when only one person is doing all the work in a marriage.