Betrayal and loyalty

My son consorts socially with my ex ( Geni and Leonnie's Daddy).  Which I am uncomfortable about.   My son, Mike, is almost 31, and if anything takes Dopey's side when it comes to Geni and Leonnie and about a week ago he started agitating for contact with me again.  He spins away and comes close again (usually when he wants something - like money, or to gain some information Dopey wants to confirm).   

He was invited to Christmas and did not come.  To the Boxing Day BBQ at my cousins, where he said he would come but didn't.  To Geni and Tony's birthday bash at FuLin, which he claims he was never invited to. ...

Last week he left rude and abusive and offensive messages on facebook, which I deleted and then Leonnie told me Mike was "there" at her dad's for one of his three annual boozeup/cricket matches and I could hear him hurling insults for her to catch and fling at me.   I quietly suggested to Leonnie that was excessively harsh.   And she ended the telephone call quickly.  

I wanted to send him a text message just telling Mike that I feel his choices are disloyalty and that if he is seeking to be closer to me, then he would not curry favour with my ex.    I asked Tony who suggested nothing would be accomplished by doing that, as Mike is taunting me looking for a reason to have a go or explode.  I am not one to hide what I feel. Or think.

It did not matter, anyways.  yesterday morning I received this text while waiting for Court with his sister.

"go and get F@#*ed you dropkick of a woman.  You are a sorry case for a mum, not to mention highly personally irrational and irresponsible.  Who said to you that I wanted to be close to you, especially if it comes with all these conditions.  As to bad-mouthing you, from now on I will do that any chance i can get. Your loving son. "

There must have been volumes of alcohol consumed and it looks like he and my ex had some fun cooking this up to wound and hurt me.   You know what - at one time a text like this would have gutted me.

This didn't. 

Mike has started living with a woman who had three small children whom he met for the first time the night before Tess, Erik and Lizzie moved into their new place.  Mike was to have helped with the move and never showed up.   In a matter of weeks he has a "girlfriend".   Since completing University, unlike Amy who finished at the same time and HAS a full time job, Mike has not secured work.

I consider what he is doing in befriending my ex as disloyalty and my ex and I most certainly are anything but friends.   he is not a teenager any more but a grown man of 31.  It is time he started to make his own way and to stop expecting a free ride because he believes he is owed.  I will distance myself a little and he can earn the closeness by his behaviour and attitude. 

Am I wrong in this?  Should I just accept ANY treatment and disrespect as he is my son?