teenagers need to be completely on board for therapy

No.

I was 16, dying of anorexia, cutting my wrists, and thinking about jumping in front of a train. Do you think for a second I was completely on board with therapy? Fuck no. Did it save my life? Absolutely.

Listen to me. Your kid needs an adult. He is only 15.

I know we want our kids to be responsible, and we want them to grow and flourish, and feel free to do that, but that isn't always the best for some kids. You sound afraid of him. You sound like you love him, but you sound afraid to take a hard stance with him. He's only 15. He doesn't understand the nuances of life and power, so he's turning into a bully, and this may sound harsh, but you're letting that happen. You're going to need to be strong, here - strong enough to take control of him and not let his moods and behaviors do the deciding.

He is getting way too much control over the parts of his life that he shouldn't be controlling, and not enough control over the parts that will help him. You need to take some control back - not through friends, not through family, not through teachers or counselors. You.

Lovingly, without compromising - make him go to a therapist. Sit in the room while he's silent if you have to. Lovingly, without compromising - make him wash his clothes. Stand outside the laundry room if you have to. Take his electronics out of the house and don't give them back. Sit at the kitchen table with him until his homework is done.

There will probably be yelling, and slamming, and hateful names. Deal with that however you have to when you're away from him. But be strong to his face. You're at very real risk of losing him to a dark path.

Be resolute - and don't even think about mentioning to him again that he has and say in going to his dad's - with that little agreement you made, you did a whole lot of damage. He was looking to you for a strong no, and you let him down. You let him know you're not on his side, and you let him know you're not willing to work on fixing him. You also probably disappointed him and confirmed his opinion of you as weak in the face of men acting like douches - you're going to need to undo that.

This is on you, at this point. You're going to need to work on him yourself, and you're going to catch a lot of horrible hate from him, and I'm sorry. I put my mom through it, too. I said and did awful things. But I was a scared, angry, hurting kid. And your son is, too.

My mom put up with me sobbing, and yelling, and was an absolute implacable bitch to me - or so I thought at the time. Really, all she did was take me to the therapist and refuse to take me home until the sessions were done. She took me to the store and refused to go home until I chose something to eat. She sat with me at the table until I ate it. She took my computer away entirely. CD player, gone. Phone privileges, gone. TV, gone. I wasn't allowed to walk home from school alone. She had to get me. I had to show her my homework. This lasted for nearly a whole year, but dear lord, did it help.

And it wasn't all bad. When I expressed an interest in gardening, we gardened together, digging up new holes in the lawn and celebrating. When we had our last therapy session, it was when we decided together that the therapy wasn't doing much more for me, but that I was getting better and didn't need it any more. When I graduated with honors, scholarships, and university acceptances, it was the biggest relief for both of us. So yeah, stuff will get crappy for a little while, but you need to let it, and you need to be awful, and mean, and strong, and you need to be a parent. I hope this helps.