I Jointly Own A Property With My Sister I Live In It And She Lives In Spain, Where Do I Stand???

I purchased the property i live in with my sister in November 06 and we each put in an equal share of £34000, hers in cash and mine in the form of a mortgage. The purchase price of the property was £61500 and the remianing £6500 was to be spent on works on the flat including the installation of a damp course and various other works. There were unforseen problems with the flat and the money was used up much quicker than expected and since then all remaining work on the flat has been funded by myself. My sister currently lives in her own property in Spain. The original intention was an investment for her and a hand on the property ladder for me, she now wants to withdraw her money from the property and the subject of percentage of the profits came up. I stated that as this was my home and because i had pur approxamatley £5000 more into the property that i should have a greater share, but she says she wants 50% of the current market value. I want to know legally where i stand on this. She will if we sell be effectivley making me homeless as it’s very unlikey i will be able to afford another property on my own, plus i feel as i’ve put nearly all of the work and a lot more money into the project that i should be entitiled to a greater share of the profits. I had considered taking a mortgage out with my new partner to buy her out, but if she insists on 50% i will be unable to do this as it will be unlikely there will be enough equity on the property. Current market value when the falt is complete will be about £85000. Any help or advice will be greatly appreciated.