Marriage is a very holy knot. It needs to be tied with someone you can trust because he is going to be a father of your children and there is a whole progeny that follows suit.
This Is definitely a sensitive situation. You Most make very good and detailed research about the person before announcing your decision. You must look into his hang around places, friends, social media, work reputation, distant family members reviews on him, etc..
All this will help you disclose the truth. Everyone needs a chance, but only the right person deserves it.
Hope This was useful