That would have been my next guess.
There isn't any "hoping." You'll have to petition the court to award you reimbursement and you will have to prove to the court that you are entitled to reimbursement which, unfortunately, is likely going to require some proof of a contractual arrangement. Otherwise, as far as the court is concerned, a 50/50 ownership is a 50/50 split.
It's time you started talking to a lawyer and review your options and potential costs.
You wrote that she refused to sell out to you. Did you just offer the $4000? Did she say, or did you ask, how much it would take to get her to sell? Might be cheaper in the long run to just offer big enough bucks. At least, then, you would still own the property.

