Isabelle:
Get out of his business, get out quickly and with as much respect as you can muster.
Demand that he show you the respect that you deserve.
-First figure out what respect you deserve. Get a VERY good sense of what rules you want followed in your house. Tell him what the rules are, don’t tell him how to follow them unless he asks respectfully for help.
If he tries to argue, don’t take the bait. He’s smart enough to figure out how to make it work.
When you lend him money, you communicate disrespect for the fact that he has a job.
When you offer to teach him to budget you disrespect his ability to develop his own system, you cheat him from figuring it out.
Cancel that damned cell phone, NEVER EVER risk your credit for him again, at least until he’s a better credit risk (ie: he pays you back what he owes with interest, I suggest 19% like a credit card company might.)
Don’t give him a ride to work unless he pays what he owes.
Don’t make idle threats like you’re kicking him out. You are not likely to do anything of the sort, even after he turns 18, and I’ll tell you why:
It sounds to me like you need him as much as he needs you. (I apologize for this in advance, I hope no one here knows you personally) Father gone, he’s the man of the house, he’s your closest peer in the house. The diffuse boundaries you have with him smack of enmeshment.
It’s not healthy to depend on your child for this much emotional support, he’s not equipped.
I’m kind of taking a stab at things here, but I bet there’s some truth to it. Realizing what truth there is to it is going to be part of your healing and what makes it ok for you to use your good sense as a parent. It sounds to me like you’ve made compromises in what you believe to be right, and I think this is why.
When he says that what he does with his money is his business, he’s right. He’s trying to tell you that the intimacy in your relationship is too much for him to bear. Step back, let him live, find your own boundaries.
Get a strong sense of who you are and what you stand for, then go whoop some ass.