Ex put nothing into house now wants 40%

silvercar

You have had sole use of the property, so could be considered to have been renting her share of the property off her. Rent money that was in turn used to pay the mortgage. Or you could look on it as you paid the mortgage and she paid rent elsewhere. Either are valid and probably more valid than thinking she paid nothing.

Now you have the situation where she has a debt (the mortgage) attached to her name that she wants rid of. You have agreed to sell to facilitate this and have lost out to the tune of your share of the legals and selling costs that you wouldn't have to pay had you stayed put. These factors allow some negotiating room.