As our children get older, they want to be treated more like adults. At the same time, they often don’t seem to be able to make decisions any better than when they were 10. Given your son's age and the fact that you support his going to college, you should use the time you have left together to get him the help he needs.
Please do NOT allow him to go off to college unless he is stronger emotionally. Even young people who are confident, outgoing and real leaders of their peers struggle to handle the pressures of college life. There are academic pressures far beyond anything he has experienced so far, and the social pressure is far beyond perhaps anything even you as an adult have experienced. Let him know that if he doesn't get help, you will be unwilling to support his college in the fall. As his parent, your number one responsibility still is to ensure your kid's safety. In this case, it is his emotional safety that you are concerned about. If he claims to be "fine" and says he will be all right, let him know that you will need a professional opinion to verify that.
