You are probably in the right legally,but he (sort of ) has occupiers rights.
What I mean is,that despite the fact that you had not authorised these repairs(nor felt that they needed doing),he IS in the house,and as such has the "whip hand"so to speak.
In order to facilitate a quick sale (hopefully,given the volatile property market) I would bite my tongue,let it be sold,let him claim back the money for the reapirs(as long as this is not too large a sum),and get the hell out of the situation.
A court would probably say that his repairs may increase the sale price,which you would benefit from,although you paid nothing towards such repairs(for whatever reason)
This is not MY view,but may be the legal one.
Dragging it out,either with or without the law can only bring you grief (on top of what you obviously have had already).I don't think it will get you anywhere to proceed further in disputing what he wants,as I have said,better to sell the house get what money you can and have nothing more to do with him.
Sometimes it is better to keep silent,rather than escalate an already bad situation,when it will (sadly) get you nowhere,and indeed may COST you money.
I apologise for not being able to be more positive.