P.G.
Kate and Emily are both right. If he is willing to take a parenting class, etc to work with you to be a father to your child - great. If he is not, then get out of this marriage. You can get it annulled and you'll all be better off.
I don't mean to be gruff, but I have to be blunt because I've been in this situation as a kid. Are you really surprised by this behavior, or did you not have an opportunity to see what he was like because you rushed into this marriage?
I am a child of 2 divorces - mom was a serial dater who kept looking for someone to "take care" of her. Please don't do this yourself and your son. If this relationship doesn't work out, the damage should be minimal because of the amount of time involved and your son's young age. Remember - every relationship you are in is not just 2 people, it's 3. Take your time, focus on your son. It will pay off huge in the future, believe me.