If she sends another one of her informative texts, but doesn't actually ask for anything, I think you should set your position on it - reply, I hope you're not expecting me to pay for any of this - I was honest in my description of the car and once a car is sold as seen, it is no longer the seller's problem. Or words to that effect.
From Trading Standards:
When you buy a used vehicle from a private individual, you don't have the same rights as you do when buying from a trader. The legal principle of caveat emptor, or 'buyer beware' operates. You have no right to expect that the vehicle is of satisfactory quality or fit for its purpose, but there is a requirement that it should be 'as described'. For example, if an advertisement says 'low mileage, one previous owner', it must be correct. You should check the vehicle thoroughly before you buy it.
Whether you buy privately or from trader, you are entitled to expect that the vehicle is roadworthy, unless you and the seller clearly agree it is bought for scrap or for spares and repair. You should be aware that a vehicle sold with an MOT certificate does not guarantee that it is currently roadworthy, only that at the time it was tested it met the required safety standards needed to gain the MOT certificate."