12 yr old w/major attitude

Hello, I have a 12 year old adopted daughter that we fostered for six months and then adopted last Nov. So it's been about 8 months. We are constantly fighting or arguing about stupid stuff. She blows up over the littlest thing. It frustrates me because she doesn't act like this towards my husband. She does what she is told when it's coming from him. We are going to counseling but she doesn't listen as soon as we get home she is right back at it again and I try to talk to her about it she says things like "whatever" and "stop talking". Last night was a breaking point for me. I am beginning to have serious doubts about whether or not I am the best person to be raising her. I wonder if she would be better off without me. I can't stand being around her. I am very guilty and depressed about the feelings I have. I know they are wrong, I know my responses are wrong, but I feel so out of control. My husband will always back up my decisions when it comes to discipline and consequences but he does not step in when we are arguing or she is being disrespectful. He is WAY to laid back about the whole thing and I fear that this will only continue to escalate if I can't get him to start taking this seriously now and helping me. I am tired of all the classes and books and counseling sessions and after all that nothing is working. I feel like I am doing all this stuff by myself and it's all my problem.