Options for leaving parents' house? NEED to get out?

I'm trying to find economic ways to move out and live on my own. If needed, my boyfriend can live with me so I'd have a little help paying for things. I've always had issues with my mom (extreme understatement) and now my parents are divorcing and there's just too much going on...the situation is not good! I don't make that much with my job, but my boyfriend and I together will have about $800 a month...but we also pay for our cars, insurance, college books, and several other things already do half hat money is out the window. His family would allow us to stay on their property, so I was thinking of maybe putting a barn home in a small corner of their yard. Those are so expensive, though and we don't even need anything that big, just the basic necessities so honestly I'd be okay living in a large shed! I just really need to get out of my house! Does anyone know a cheaper way to do that? And is there anywhere I can go for help? Any serious suggestions are welcome and appreciated!