Commercial law, litigation, contracts, IP, property law
You say all three of you are on the title. How is the title worded?
Does it say as joint tenants? or does it say as tenants in common one third share each? Probably the latter???
What ever the case while all three of you are living you own one third of the place and if it were to be sold you would be entitled to a third of the net proceeds of the sale.
If you are willing to accept less for your share without the place being sold it is up to the parties to negotiate what that amount may be.
In the long term you are probably better off remaining an owner so that when your mother passes you will probably remain owner to your third and what ever part of your mothers share that she wills to you.
If you do not wish to put any more money into the place you could remain a one third owner but reach an agreement with your brother about allowing him a greater share of your mothers part as compensation for the larger amount he will have paid in to renovate the place. That is probably the negotiation you should be having now, rather than selling yourself short by pulling out.