V.W.
Whew. I have a 12 year old son as well. They have that "I'm a man" but "I don't want any responsibility" thing going on. They have a lot going on with them. My son is a GREAT kid. Truly. But boy can he drive me up the wall sometimes too. And the attitude? blech. (How's that for sympathy?)
Do you have any help with him? Any male role models in his life? A coach? A Sunday School teacher? An uncle? What about his dad?
What sorts of things does he like to do? My son has been in karate since he was 5 and the role models that he has in that karate school are PHENOMENAL. Old guys, middle aged guys, young men, high school kids, .... and then the kids who are SMALLER than him that HE gets to mentor.... It is an amazing dynamic. Could you get him to give martial arts a shot? They are really supportive of single moms, and also really expect a lot of respect, honor and integrity out of their students.