Despite the fact that you have paid all the loan payments secured against the house your ex still owns half of the property. The bad news is that he is entitled to half of the value of the property. The good news is that the valuation is set at the date of separation (when the relationship broke down, even if you remained living under the same roof for a period). so any increase in valuation in the past five years is yours. of course the 'crash' may have wiped out any of that increase.
If you want to own the property solely, then your ex will need to transfer his half of the property to you. He/she may choose to do so for free if, for example his share of the assets are equal to or more than his share of the debt secured on the property. The property transfer will require a solicitor for each of you to act on each of your behalf. No doubt each solicitor will make you both aware of each others entitlements. I think I'd rather be in your ex partners shoes than in yours though.
How long did it take you to dream up your username? Honestly, the mind boggles. :-(