You did what was best for your son. You also will not have to beg him for anything anymore and he won't be able to use his willingness (or unwillingness) to provide for your son as an emotional tool anymore.
Funny thing is, I really think that it is way more expensive to have teenage children live with you than to pay child support. I know in my budget, when my step daughter is here for the summer I spend at least $600 more a month just for the additional food, water and power. Not to mentions how much we spent out of his pocket on gifts and activities while she was here.
On a bright note, I think my ex (father of my older children) has finally figured this out. I think he has also finally given up on the idea of blackmailing our kids to try and persuade them to come live with him. He actually said to my daughter that if she would come live with him he wouldn't have to pay child support anymore. She was so offended that she never considered it again.
My ex has a wonderful new fiance. I really hope that he can keep her. She is older than him and has lived through all this with her son (who just went off to college). For whatever reason, he now is willinging to do some very nice things for our kids, in addition to paying his child support and has not said anything like "that's what child support is for" lately.
Finally after 8 years of marriage and 10 years of divorce, I think he is actually putting the interest of our children first. Right now it is a peaceful happy time for our children. I am so happy about that today.