Well, your son is older (but no wiser) and will soon be legally (if not emotionally) classified as an adult, and no longer your responsibility. In this respect, I would encourage you to give him a lavish farewell party, a small sum of money to tide him over, and your best wishes for his future happiness in whatever pursuits he so chooses. From there, you can begin to reclaim your life.
Yes, you are obligated to care for him until such time, since you made choices that proved to be unwise (- perhaps relinquishing much of your authority for fear of lost/reduced affection?) - that is not his fault, if you can follow my drift, but you still have time to simply say no and let the child rage away in petulance (but don't forget to pass on the costs for damages!).
Was there any legally binding agreement re co parenting arrangements that you might wish to pursue through the courts, or did you inadvertently place this burden upon yourself? The tough news that is always hard to hear, is that your son owes you nothing - it's harsh, unfair, and disgraceful; but only you had the obligation - the rest must come at the behest of the individual.
Love your son for he will always be, and remember that his frustrations play out from his upbringing and experiences. Time may mellow him to see the bigger picture, but there will surely be much suffering before that eventuates, so feel for his struggles just a little, and hopefully you will find the love you seek and deserve - it is there, but very deeply concealed.