Put yourself in her shoes. If she outs you she is putting the tenancy of where she lives at risk: Landlords often turn a blind eye to what goes on in their place, but if it becomes well known then he has a good reason to evict her. She also has - potentially - fears over things like benefits fraud.
If she owns her place, you would think discretion would be her top priority.
The thing to establish therefore is: does she work on her own account, or is she run by a pimp? By the sounds of it, she is independent.
The remaining risk then is being seen going in or coming out of her place by people you know. This is where the stock phrase "only you can answer that question" comes in. I'm sure you can be creative with things like the postman mis-delivered a package and she invited you in for a cup of tea.