(((((hugs)))))
It is time to call the social worker about foster care again. Whether she apologizes, does better for a while, or kicks you in the stomach, this situation isn't healthy for either of you. If you need a second job and can find an easy one, it would likely be worth it. Things have been escalating for a while now, and are going into the place where the danger of physical abuse is very real. Sometimes a family cannot exist under one roof, and needs to be a family of different addresses. I wouldn't turn down any therapy, even if you don't really want to see her for a while. The therapy is what will help you both in the future, and if it is needed to keep from paying child support, well, think of an hour or two of therapy a week as your second job. It would be a lot easier than being a greeter at Walmart in some ways, and harder in others.
I have long thought that one of the biggest parts of good parenting is when to say "Enough.", to make a big change to stop yourself from destruction or from abusing your chld. I got Wiz out of the house when it became clear that if he stayed one of us would be seriously hurt or killed and the other hurt or killed or in jail. I didn't trust myself or him, and if he got through me he would have killed J and possibly T. You don't have the other kids, but you do have a seriously escalating problem. I should have stopped before we got to that point, but that is hindsight. You can stop before it gets to that point, and I would make that call as soon as possible if I were you.
DDD is right about what the stress will do with your diagnosis's. Chances are you will have a huge physical toll from the stress, and it will take much time to overcome. I am sorry.