It’s your call. Just don’t bother changing him, because it won’t help anything. You need to take a decision on what you want. Are you okay to be in a relationship with a guy who is a playboy? You might good reasons to stay put, but fidelity should not be one of them. Remember that there are lot of guys out there who are “one” woman men. In the end, your peace matters more than his habits. If you feel used, then walking away is still an option.