I had a DH with man child syndrome. He's getting worse by the day. I left him after 20 years. For 15 years with a child and him a permanent 14 year old. I don't exaggerate. It is wearing having two kids and no adult support despite having what appears to be another adult in the house.
He very quickly found someone else but he is still rewriting history too. I am responsible for just about everything that is wrong with is life. He has a lovely new girlfriend who is much prettier than me, younger than me, sexier than me, cleverer than me, kinder than me, more loving than me, wealthier than me, prouder than me, works harder than me. But for some reason still he is angry with me and looks permanently like he's going to blow a gasket.
Man child syndrome is a very complex but common problem as far as I can make out. It also causes superiority complex, deafness, short sightedness, temper tantrums, inability to get out from under a duvet, inability to deal with other children and general laziness.
I too receive regular text messages and emails about just about everything that are about nothing. Luckily I can block the email but the texting is more difficult. Also luckily my daughter is much older and he can contact her himself by telephone and no need to contact me at all really. But he still does it as a way to feel he's still got some measure of control. If he doesn't get any reaction he eventually gives up though.
With a man child you probably won't get any respite until he's run out of guns to roll out or meets someone else to concentrate on. Then the kids suffer as they are too busy chasing after the new woman to give their kids a second thought.
I have deep sympathy for you. It is a brave thing to give up on a man child because you spend years hoping they will grow up and change but they never do. They just move on to the next woman (mother replacement). It is wearing but better cut and run not like I did and let it run on for so long our daughter begged us to separate.