Sold A Car That Turned Out To Be A Clunker - Am I Liable To Re-purchase It From The Buyer?

I sold a car for $3k with everything I knew disclosed: Check engine light is on, and engine knocks. My mechanic told me it can be fixed with a relatively cheap fix - replace the coil pack for around $150. All of this was disclosed and car was sold cash for 1/2 of KBB value to account for this.

2 weeks later the buyer reaches out and says a mechanic she took it to says it needs a new engine. Later she took it to the dealer who also said it needs a new engine. I suggested she take it to mine to do the coil replacement, and if that does not work I will refund her $2k and she can keep the car. She refused and only wants me to re-purchase the car from her for the same amount she paid otherwise she will sue.

Am I supposed to re-buy the car?