Buyer wants refund
12 days ago I sold my barrel horse. The buyer came out and rode her, then decided to purchase without a PPE. We agreed on a price and signed a bill of sale. 12 days later she calls me saying the horse is lame and she is demanding her money back. She took the horse to the vet for being lame on both fronts 10 days later. She stated that the vet stated it was a pre-existing condition but did not take any X-rays. I told the seller the only lameness she had was from an abcess on the medial(inside) front right heel, and that if she was going to ride her heavily I suggested shoes as she was currently barefoot since I never kept her in heavy work without shoes and didn't know how her feet would hold up. The mare has never been lame on both fronts while I have owned her, I also have clear x rays of her front feet from when I bought her two years prior.
Our contract states that the mare "is in good health" which she was when she left my property; her feed were trimmed two weeks prior, all shots coggins and deworming have been kept up with.
The contract also states "no guarantee or warranty, expressed or implied", which I relayed to her. She is now stating she will be at my barn tomorrow (the time she stated i will be teaching riding lessons at technically be at my place of work) with the horse expecting her money or another horse and mentioned my other horse, who would not be suitable for barrels any time soon as he is a yearling.
She also called me while at my other job numerous times an hour sometimes 6 times in a row.
Does she have a case against me, and can I do something about her harassing me?