Husband in a family dispute feels slighted?

My husband bought a farm at a very young age with his brother to split, due to his great credit. It's been many years now, and it seems the split they originally set up is not fair. The one family got the house on the property, which has 6 bedrooms and a garage, which they feel should be exclusively theirs. They have foue adult incomes going into the home and four kids. My husband got an old trailer. The two pay the exact same amount on the mortgage. As he got older, met and married me, we realized the trailer we lived in was not safe for children, we have two, but were financial unable to get a new one to replace the one falling down around us.
One in the other home had a trailer they wouldn't ever use that they were still paying on, and offered save on lot rent if we give what we could. We felt we had little choice. The new trailer has needed much work due to all the damage done by the prior tenants. Now, we are being told that we have to pay a set amount every month and owe 450 in back pay for living there. We gave a chunk of our tax returns and paid for the taxes on the trailer and fixed it up, and we are told we still owe.
We don't have any extravagants. We haven't our own garage. Heck, we technically don't own anything on the farm but our cars, but we are now asked to pay more per month to live on the farm without owning anything on it than the brother's family who has the big house and more income. Are we over reacting, or should we put our foot down and say no?

Read more: Husband in a family dispute feels slighted?