Tough spot, but you have to continue to be the bigger person here and not think in terms of ultimatums, like that she needs to move out if she doesn't change. That's not fair to her. Yes she's not being fair to you, but she's a child and didn't ask for any of this situation.
If I were you, I wouldn't be angry with the girl, I would be concerned about her feelings and would talk to my husband because of that. I would want to know what she's upset about so that she can work through those feelings and feel peace in her home (your home), where you should also feel peace. Tension is no good for anyone. I think you should tell him, of course, but make sure that you're doing so out of concern for her, not because you are offended. I would let him know some time that you have something you need to discuss privately and would like to know when would be a good time to talk.
Then when that time comes (when she is NOT around and can't overhear you), say something like "I'm worried about Sally. When you're around, I know that everything looks fine and she's engaged and communicative and happy. But when you're not here, she acts differently. For example, she spends all of her time in her room. And I don't know if you've noticed, but even when we're all here, she won't be in a room with me when you walk out...she walks out too. Even if you just get of the car to get gas, she suddenly stops talking until you get back. It's so different from how things used to be. It started happening [whenever] and I didn't say anything for a while because I wanted to make sure I wasn't imagining things. I am really concerned and wonder if she's upset with me directly over something or if she's just upset in general about something and this is her way of showing it. What do you think? What can we do to find out what's going on with her?"
Please don't let this get to a place where you dislike her. Yes she's 17, but she's still a child and needs your love. We don't get to be pissed when our kids push us away, and they all do it at some point. Maybe it's just her way of dealing with normal late-adolescent transitions - she must be thinking about what comes after high school, becoming an adult, etc. This age is a normal one for difficult behavior because our kids need to distance themselves a bit emotionally to prepare for the physical separation that often comes with college. I work with a lot of kids who are Juniors and Seniors in high school and many of them are just awful to their parents (or sometimes just to mom but are civilized with dad). It may be that she has "targeted" you because she feels safest with you and knows that you'll be there no matter what, like a biological mom would be. Or it could be her way of working out some angst about the blended family, and you are the convenient target for "replacing" her mother or whatever. I know that often when my SD seems mad at me, she's really mad at her mother, who abandoned her last year.
Anyway...there could be any number of reasons for her change in behavior. Have some compassion and don't ignore it. You won't know what's going on until you all talk about this. If there are a lot of buried feelings, then some sessions with a family counselor may help a lot. Best of luck to you, and try to not let this get you angry.