She has moved out, for three months renting another house,, nothing was in writing or any agreements made before she left. I have made all the mortgage payments for the past seven years and have all my check registers from my own account .I would like to know what I can do to get her off the dead of the house. She says she wants half of the house but we owe more than it is worth, I'm willing to keep making the payments

Since she is a co-owner you will have to buy her out. So first question is whose name is on the mortgage? If both of you, you will need to buy her half and refinance using your credit only. If the house is truly under water her equity is negative, so refinancing with her name no longer on the mortgage would be more than fair. You may have to come up with some extra cash to do the refinancing, as the loan amount of the new mortgage may not be enough to pay off the old one.