Nothing. Her name is on the deed, so she has just as much right to be there as you. On the other hand, you have a right to have any guests you want. Move in a new gf & be obnoxiously sweet. Or move in your friend whom she can't stand. She'll leave in disgust & agree to deed the place over to you.
If you don't like those options, sue her in court to partition the house by sale. The court sale costs will eat up any equity you have & BOTH of you will end up owing $$ to the court. You can buy the house oon your own. When given a choice between giving you the deed for free or having to pay a court to force her to give you the deed, she should pick the one that won't cost her money.
Next time, either get married first or draw up a contract that specifies what happens if you split up -- who gets to buy out the other on what terms.
She may be refusing to sign the deed in part because she's on the mortgage. Offer to assume her part of the mortgage so that she has no liability for th edebt if she deeds her interest in the house to you. You'll need to hire a real estate attorney to help.
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This is not legal advice and you are not my client. Double check everything with your own attorney and your state's laws.
