It sounds like you have made a very good friend, and even though you are developing deeper feelings for him, he isn't ready to be in a serious and committed relationship, and frankly does not want one. He is telling you his truth and you have to accept that no matter your feelings for him. He will be unable to be the type of man you want in your life.
It is easy to want to convince yourself into believing that maybe you will be the one to change him, and that he will want to be a better man just for you, but it is this type of thinking that leads you into the 'I can change him' trap. This is a tough dating trap to be in, because you will realize that he won't change, and that he'll be the the non-committal, cheating drunk he told you he was. At that point you'll be emotionally attached and physically involved, and the pain of a break up would be excruciating. You'll end up hurt, disrespected, and you'll eventually lose the friendship you once had.
Don't sell yourself short! You can't wait around in the hopes that a guy who is unavailable will suddenly change his mind and decide he wants what you want. You'll be waiting forever, will catch the crazy, and will grow resentful in the process. Start by setting some boundaries for yourself so that you don't cross the friend line into flirtation or something more. You have to make a concerted effort to make sure you don't end up in compromising positions with him (i.e. don't go drinking and partying together, don't hang out at his home, stay away from overtly sexual conversation).
What you can do is keep yourself open to meeting new people. You want a man who wants the same things that you do, so you need to continue dating. Once you shift your attention elsewhere, you will open yourself up to finding someone who is ready for an honest, loving and committed relationship.
Rebecca Brody is a relationship coach and columnist in NYC. She hosts ImprovDates.com, and works with private clients. Send your questions to Brody@TheLuvCoach.com or visit her at www.TheLuvCoach.com.