Nutley, you need to have a very open and honest conversation with her. Does she see you as just friends that have fun fucking, or what? Ask her if she is interested in a date, no money / sex involved. I do honestly believe that it is very possible to have a relationship with someone, even if their job involves sex, and even if from your point of view, it's going to be an affair.
However, working girls are just people, and even civvie women (or men) can be manipulative and out for what they can get. It really does depend on whether you think you trust her, and what she says / does in response.
If she says "I will never take a penny off you from here to evermore", then that's a good start.
If there is any shortfall in ANY of the above, then be prepared to be taken for a ride and have it cost you thousands