You can do this, Lucy. (I don't see why you have to pay for the plumbing either, btw.) I used to buy food in bulk from a food co-op. There are thrift stores, yard sales, many ways to cut corners. Avoid eating out.
I left almost 20 years ago and within one year had one kid in college, then the next year two in college. It was quite difficult financially. I got into debt for a while, what with having to support my own household and making sure the college bills got paid on time. My ex eventually paid his share but not promptly. However with the perspective of 20 years: everything worked out just fine.
My family helped out too, in the very beginning. It was embarrassing for me to accept their help but I was grateful to have it.