My only son

Hi..... Sorry to hear your son is still acting immature at this age but you have given him some 'tough love' by kicking him out. He won't learn responsibilities if he always has you to run to and dust him off. With you allowing your granddaughter to spend time with you on the weekends is just you being a loving grandmother- he sounds selfish and jealous- if he has an issue with that. The best you can do is hold your ground and let him realize he is in a hole of laziness and irresponsibilities- and that the only way to stop getting in deeper is to STOP DIGGING.

Sadly, there is nothing at this point you can really do to influence his behaviors. He is an adult male acting like a boy, and while there are many reasons that influenced his development into this person with no character or sense of responsibility, now the ball is in his court! The best you can do is try and be a positive influence in the lives of the grand children, so that when they grow up, they will not repeat this negative cycle.
Best of luck.