I wish I had some really smart helpful comment for you but right now, I don't - I'm also pretty sleepy! Sorry! But let me say that being the parent of a soon to be 18 year old and having gotten to know most of her friends, it's not easy being a parent at all. I don't think Cody's father should have listened to the conversation, that's wrong in my opinion.
Somehow we (generic term for everyone) always feel attached to our first love. It sounds like you and Cody are still attracted to each other. You mean well, and perhaps giving him a bit of a distance for a while, and letting his parent cool down might be a good thing. Of course if he calls you (Cody) threatening his life again, do talk to him and if possible suggest other help for him, as in a Guidance Counselor at shool or anyone else who he could talk to. It sounds like he needs an outlet.
It's good to vent and writing is pretty helpful!