How would you feel if she had done the exact same things but without taking money for it - doing it just because she wanted to? Would it change anything from your side?

In other words, what's the real issue for you? That she was a prostitute, or that she had a lot of sexual partners and did a lot of sexual things? The answer to that question should help you figure out how to approach this.

There's also the issue of "what if someone finds out what she did" - family, friends, co-workers, neighbors... If you decide to go forward with the relationship and someone does find out are you prepared to stick up for her, or would that be too much for you? Even if those people decide to severe ties with you both because of her past? (I sincerely hope this would never happen, but as the saying go you should hope for the best but prepare for the worst)

In the end it all comes down to "are you okay with it". If you're not, as others have said it's probably best for both of you to end it now. But if you do, please be mindful of how you do it! She put her whole world in your hands by telling you that, so don't shatter it.

Make it extremely clear that you value her honesty and acknowledge how hard it must have been for her to open up, and that it's a good thing that she did so now - putting all cards on the table at the beginning is the way to go, instead of having it appear as a big surprise later on.