Bismihi ta'ala
As you know, the primary requirements for spouse selection is that the prospect spouse adheres to religious precepts and carries high moral standards.
These two conditions are of utmost importance. This is why both men and women must keep our chastity and be as righteous as we can, which means that we save ourselves for our spouse-to-be, and try to observe as much Jihad al-Nafs in avoiding pursuing our lusts until marriage time.
Of course, this is why it is so important to get married at a young age. It's also why we need to preserve our dignity and keep a good reputation. Obviously, sleeping around with prostitutes goes against all of these basic social and moral requirements that any wife would want.
We might say that this person has a bad past, and that he regrets it and is shameful of it, so why hold it against him.
The answer to this is, yes, we should not hold something against someone who has changed their ways, but it is still a risk of to what extent can one rely on their past not affecting or not creeping up again. What kind of assurance is there that such an individual has not turned into a promiscuous person, or maybe even a womaniser.
I would say that although this is something confidential, and personal, for you to completely dismiss it and go ahead with the marriage, such a decision might have negative repercussions.
Please consult with your family members, do some further background investigation into this person's life, and do not emotionally invest into anything unless you are absolutely confident that you are making the right decision.
With prayers for your success.