Once a cheater always a cheater my dear. If it's in his heart to be selfish like that once, rather than work out your troubles, it will be in him to do it again. (Same goes for women who cheat by the way)
Unless you really plan to give up the current boyfriend to marry a cheater, I would probably talk to your current boyfriend and explain to him what happened. It doesn't sound like from this question that you are ready yet for marriage in general. Wait until you are mature enough and truly ready to take on all that a lifelong marriage will entail. Best wishes to you..