Buyer suing seller after sale

[Eran S.]

Hello fellow real estate-ers, wanted to share the following experience and get your thoughts:

I sold a house (primary residence but was vacant for a year) about two months ago. 

The house was partially renovated but with visible gaps. During the inspection period the buyer got his own inspection and tried to get me to perform repairs, I refused but he negotiated additional $5000 seller's assist (in addition to $5000 seller assist he negotiated before the inspection, total $10000 in seller's assist), and we reached an agreement and closed.   

Additionally, I provided him a previous inspection report (done by a buyer who backed out) for his review prior to making an offer. Both inspection reports called out a long list of repairs, although the previous inspection had more issues that I addressed before the new buyer's inspection.

Buyer's claim: buyer send me the attached letter claiming that he bought the house because he thought it was renovated well and now he has to spend money on renovations and repairing damages resulting from the unpermitted work

My claim:

The buyer had never asked for permits and neither me or my realtor ever claimed permits were pulled for any work. 

Prior to inspection the buyer asked if the plumbing was upgraded and my realtor replied that "some plumbing was upgraded and some is old" not specifying which rooms are updated.

Buyer claims in the letter that he had no reason to expect problems with workmanship. That is inaccurate as the buyer did notice a lot of workmanship issues and even negotiated seller's assist when I refused to perform repairs.

Btw this house is in Virginia, which doesn't require detailed disclosures from the seller. And I never made any representations regarding permits.

Please let me know what you think!

Do you think this a series claim? How would you respond?

Letter:

Thank you!