You gotta do whats best for you, at the end of the day you are are by yourself and you are all you gotta worry about. Till you have your own family, that changes things. It sounds like its not right for you to be with him and its not fair to him. If you are not 100% there, you gotta end it. It will hurt now, but in the end you both will probably be better off. I was all for you trying to work it out and get some freedom from him till you said you still love someone else, that aint right. You gotta work on that. Good luck! PM me if you really feel like you're in need of someone removed from the situation to talk to. I have found that helps alot through situations such as this.