jackthedog, I just read your thread and I seem to be missing how your custody arrangement is set up with your exAH. I feel like I'm missing some pieces to your puzzle.
We are talking about your 13 year old son. By the time a child reaches the age of 13 most of their character is already developed. I have read the most important age of child development occurs between the ages of birth to 5 years old. Your son is reaching that frustrating age of being a teenager. Nothing shakes a parent's confidence as much as the onset of a son's or daughter's adolescence. It's not unusual to feel our teenagers have
"porcupine-like spines that bristle whenever we get near them", or
"gives off hate rays the minute we step into the room". Their response to everything we say is a groan. Sometimes we get furious, but mostly they manage to make us as unhappy as they seem to be.
The real cause of turbulence, is the teen's own uncertainty about who he is, alongside his eager need to establish a sense of identity. This involves self-questioning and self-discovery and self-development across a range of issues. Parents become mirrors: teens want that mirror to reflect back to them the vividness and clarity they themselves do not feel. A teenager's real focus is on a parent's acknowledgement of his maturity and capability and human value. They are fighting to change their relationship with a parent, to make a parent see that they are not the child the parent thinks she knows. They want to shake a parent into an awareness of the new and exciting person they hope to become. Teenagers can push us, their parents, into a
"rawness of feeling, where you say more than you otherwise would." Perversely, teens expect the parent to appreciate who they have become, even before they know. Therefore, in the emotional exposure of quarrels with parents, teens clarify and demand recognition for the new person they see themselves to be - or on the way to being.
As far as your exAH, as I was on my way home from my last counseling session, I was telling myself,
"My DDH is JUST to old for me to raise him, any more"! 
Typical Teenagers
Happy, sad, sleepy, mean, Feelings often change, a common act of a typical teen, I find it rather strange.
Talking to a friend, or sending them a text, they talk for hours on end, what’ll they think of next.
They’ll leave their room a mess and give cleaning it a miss, but yes I must confess to also doing this.
They think their folks are ancient, and utterly unfair, the result is to ignore them, before they start to swear.
Their music cracks the ceiling, and makes their parents fume, emotions always reeling, and more time in their room.
Being a teen may seem pretty bad, but from experience I can tell, it’s much worse for the mum and dad, for them its living hell!© Eddie Gee
Just my personal opinion. Take what you like and leave the rest.
Love and Peace,
Phoenix