Ok she is your client for your horse care business, so she also knows about horses but is bored, nosey, and wants to show off her own horse knowledge.
If you aren’t telling her anything important then what’s she getting her teeth into that gets under your skin?
I would definitely keep anything juicy like police out of her sight!
She’s lonely and wants to chat, but if she has you stay beyond your paid time then you are losing money.
Alternatively come prepared with horsey topics that lead away from you and your business. If she’s older ask her about how she rode as a kid. Ask about old competitions. Ask about her favorite horse. Ask her about the personal lives of her current horses.
Or about anything in her house, baking or canning or crafts or whatever she does.
Lonely people like this don’t really want to know about you. They just want to hear themselves talk at someone. That’s why they are lonely as noone wants to visit them. Sometimes there’s a bit of undiagnosed autism spectrum too.
Feed her topics that let her talk about herself and her own horses, and she well forget about talking about you. Also put a timer on how long you linger after your chores are done.
She doesn’t care about your business really. She just thinks it’s a topic you will find interesting and stay with her longer.