Forced repair

I live in the FMH, I am willing to buy my ex out, but the valuer has given two valuations, one with repairs and a lower one without. My ex's solicitor appears to be claiming that I can be forced to pay for the repairs and pay the higher valuation, can they actually do this? I dont have the money to pay for them and I suggested the valuation of the property in the current state is the one that should be taken. Any advice?

Why are they suggesting you should solely be responsible for the repair?
Have you lived there for a long time on your own?
What is he nature, and likely cost, of the repair?

I have no idea why they think I am responsible for the repair, they want to gain a retrospective regularisation certificate for building regulations and take a higher valuation than the independent valuation based on the current state of the property. I have lived here with my children for just less than 2 years, the repair cost is circa 8-10k, including the certificate. The ex's solicitor claims that if necessary they will seek a court order to force me to make the repairs. They also sent, afterwards, a without prejudice letter stating they would accept less than the higher valuation if I purchased the equity but it is still 35k more than the surveyor valued the property at and more than I can afford. The ex's solicitor is incredibly aggressive, refuses to respond to issues I raise, I asked for evidence of some of the statements on the form E and she won't respond with it, constantly asking for more and more financial details many of which she already has.

Is the need for the repair because of something you have done to the property?

Not at all. Building regulation was provisionally given subject to compliance, we never did the required work and the provisional granting of regulation lapsed.