Kimmerz, You asked if there is a book out there that discusses the apron string effect. As far as I know, there isn't one written about it. I learned about the apron string effect from other posters when I came here back in 2000.
As a wise elderly lady once told me, you will not get rid of someone going through a crisis, i.e., they hang on forever and a day. Why? They still have an emotional tie to you no matter what,i.e., they are children in adult bodies and have to grow up. Once they grow up, they have this need to still hang on to what they once had. Per this lady.
Generally, when a couple separates/divorces, they go their separate ways because of things that have happened in their marriage. Most "sSane" people do not keep poking at the lbs. They work to help sort out the finances, the assets, etc. Mlcers don't do this because they are emotionally immature and leave it all up to "mom and dad" to take care of it.
I agree w/Bea's posting. My xh still pops out of the woodwork every now and then. For example, he sent me an early birthday greeting in August. He's not done that in a very long time. The postcards from Oz are a way of putting their hand on the pulse to see if we are still there.
I know that his texts bug you, but all you have to do is say thank you and delete them. It's his way of staying in touch w/you. If you ignore his texts, he will become annoyed and angry and you do not want him to take it out on the girls or yourself.
I know you are done...but he's not...dig deeper for more patience and recognize that he's still a little boy fighting to be recognized and admired by his "mom". He's still out there exploring and like ET, phones home periodically. It will get better in time, but he's still got a ways to go before he settles down. His texts about his schedule aren't worth getting your blood pressure up over.
Try to enjoy your day.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.