X girlfriend and the house

Hi there,
I am not married or divorced, but I am dealing with one of the same issues. My girlfriend and I broke up. We bought our house in 2007. My name is on the mortgage but both our names are on the deed. Strangely our house is not under water. The tax value and value from cyberhomes.com is about $20,000 more than we paid for the home, but we got it appraised in 2007 for the lower value. I put in all the seed money for the house, the closing costs and all that mess to the tune of $3,000. I have paid the mortgage, electric, gas and utilities all by myself for the entire time, plus about $3,000 in principal above what was required with the minimum monthly payment. I have paid for and performed repairs myself. Now she is asking for half the equity using the tax value of the house. She wants $10,000. We both worked while we were together, but the entire contribution to the house was mine aside from her paying the phone/internet bill and groceries. I don’t have $10,000. I doubt the house is really worth the $20,000 higher price. I am living there now alone.
So here are my questions: If the ED issue went to court, would the fact that I have invested so much more than she has in the house be considered. I think she deserves more like 10% instead of 50%.
If they stick to the $20,000 in equity number, can a judge say that I only have to pay her a certain percentage (other than 50%) of it to buy her out, or will I be forced to sell it.
Can she be required to pay part of the mortgage now on the house even though she is out of the house. I am thinking about taxes, and insurance. If the house goes on the market and I move out can she then be required to pay half of these bills and yard maintenance.
Thanks for any help. This forum has been invaluable.

Family law is in applicable to this scenario. The two of you own the home as tenants in common, and you will have to pursue an action under real property laws in order to have the equity divided. You may present evidence in court as to why you should receive more of the equity based on your greater contribution.