No wonder you're stressed. What a horrible situation.
Of course there's no easy answer. However, my advice is to focus on what you CAN control.
She is old enough that she is going to say what she's going to say. You do have a lot of control over her in terms of money. There are many bad decisions she can't make if she can't afford to, so I recommend you make sure she has very little money. If you currently give her cash for lunches and transportation, I'd switch to pre-paying where possible.
Here's what I think you need to consider very carefully without automatically dismissing it. Again, I feel sorry for you and am saying this in the hope of helping with a solution.
I have never, ever encountered a troubled kid from a perfect background. There must be a problem somewhere. If it's not psychological, then that increases the likelihood that it's about the home. You need to take a good, hard look at the situation at home. Is there a parent with a hair-trigger temper and unkind words? Is there yelling? Is there drinking? Is there a sibling with challenging needs? Is there poverty? Is there someone who is overwhelmed with work stress or depressed? Does she have a weight problem that causes her to be bullied? Is she struggling with schoolwork?
For me, there's a clue in your comments about her. They're harsh but there's no attempt at deeper insight. You go into detail about how you're reacting to her. You say her behaviour at school is extreme. But there's no speculation whatsoever about what's going on and no evidence you've asked her where all this is coming from. That's a red flag. Is it about not wanting to type it all out or have you really never wondered about what her problems actually are?
Please ask her.
Can you afford to get a family therapist who can start hashing this out? YOU and your husband are going to have to be willing to accept criticism and act on it if you want to have a chance at improving this situation. It is not going to work to sit back and point the finger at her. It is possible that something in the home is causing this and because she is the one with the least power to change anything and the least maturity to process the situation, the frustration is coming out in bad behaviour.
I think that when a family dynamic is damaged to such an extreme, it makes sense to give everyone a break. Is there any kind of programme you could send her on or a relative you could send her to where she could calm down a bit and fill her days with new activities? Start asking around at your GP and local churches and youth organizations. It's so hard to get a place on anything these days but give it a try. If you don't get anywhere, ask her what fun hobbies she might want to do and if you can afford to sign her up, do (to give her a break from her usual situations at home and school). Good luck.