In the interest of your relationship, would you continue to converse with this person?

Say for a few years a couple years ago you slept with whomever you wanted as often as you wanted. You were single. you considered all those poeple you slept with to be friends with benefits. Now say a good portion of those people fell in love with you, but you don’t have the same feelings. Now fast forward to now. You’re in a committed, monogamous relationship, and the two of you plan to be married when the conditions are right. All those poeple you slept with are a bit bitter about you being in a relationship because that’s what they wanted with you, but you said you weren’t ready or whatever. Now all of those people but one can accept that you’re in a relationship. Remember you’re still friends with these people, so you still talk to them as friends. Now about that one person who cannot accept your relationship: They continue to flirt, send questionable messages, reminding you of how good things were, admits they’re still in love with you, and thinks the two of you still have a chance.
In the interest of your relationship, would you continue to converse with this person? And how would you feel if the person you’re in a relationship with asked you to no longer have contact with that person?