What I think is more important is how you react to being hurt and having your trust destroyed. Somebody is going to hurt your children sometime in their lives. You can teach them how to react to it with self-respect. Stand on your own two feet, tell them that what this guy did is not okay and you will not let him do it again.
It's not our job to protect our kids from the inevitable, it is our job to teach them how to live to be the best person they can, and to never be beat-down by life. They need to learn a broad range of emotion and how to deal with it. They'll learn it from you.
What I *wouldn't* do is promise them 'no more dating, no more relationships, no more meeting people'. Of course your home won't become a brothel (lol) but those promises give control of your romantic life to them instead of to you. Make commitments to yourself, if need be, but let them know that love is good, sometimes it hurts, but ultimately you are in control of your own destiny.
Good luck!