Any financial contributions you make to the repairs need to be fully documented, so that when the financials are sorted out the settlement can be adjusted to work out fairly. E.g. if he buys you out he has to pay you back the contribution that you made to the repairs. If you sell the house the division of the proceeds needs to reflect who spent what getting it to the state that it could be sold.
The only thing I wouldn't advise is that you hang around for the divorce financials to be sorted out - if water is getting in then the condition of the house can deteriorate rapidly, and cost more to fix. You do need to check that the quotes he has collected for the work are a fair reflection of the costs - to ensure he isn't inflating the cost to screw you financially and then getting a kickback from the builder... Get your own quotes to cross check