Buying a brand new house that the builder won’t finish. Is that even allowed!?

We are buying a brand new house. By the time we put in an offer, everything was bought and almost finished so we didn’t get to pick out anything. Which is fine. We put in an offer and they still had to put in the kitchen, carpet, doors…. so here we are, we can move in on Monday. I went for our final walkthrough yesterday. I found out the builder thinks he can get more money than our offer so he wants to back out. But he accepted it and can’t. So I guess he isn’t finishing the house. The carpet wasn’t done professionally. He isnt putting any handles on any cabinets, bathroom or kitchen, he isn’t even cleaning it. It looks like a construction zone. Dust and paint everywhere… hasn’t vacuumed, won’t vacuum… He says he is done and that’s what we get or we can back out. We don’t want to back out. We are literally living with our neighbors because he has taken longer on this house than he was supposed to and our house sold on time. So we are homeless. We don’t want to rent or buy a different house. Even with the problems that this on has, we want this house. But I’m angry and I think he should have to finish it. I don’t understand why I have to hire a lawyer if he doesn’t. I don’t know how to just let it go. I have tried models, but none of them come out to the result I want. I either want to have the house finished or I want to be ok with the house as it is. How do I change my thoughts? Every time I think about it I think of the carpet and how terrible it is. I will probably just think of it more when we are living there and I see it all the time.
C: house not finished
T: he should have to finish it
F: pissed, confused
A: dwell on the situation, constantly question why this is happening, don’t hire a lawyer because it’s not worth it, live with it
R: be in happy with house and angry at builder

Also, we live in a tiny Wyoming town in the middle of nowhere with 2k people. So being angry at the builder is bad. I will see him often. I even want to start badmouthing him on fb so people won’t trust him, but this is sooooo not needed and it’s just me being a jerk. I won’t do it.

C: house not finished.
F: content, satisfied
R: be happy and excited once again to move into our new house and feel like it’s just right.

I just want to cry.