What can i do with my grown son

I believe that this is more common a problem than you would think. Maybe not in exactly the same way, but alot of men have been having trouble getting their act together.
If I could be blunt, He's not your problem. Once he reached the age of 18, he no longer was your legal responsibility. I know it's a tough cookie to bite into. But although he is your son. He should be his own man. I have had a relationship which a man that is almost EXACTLY the boy you have described. And his mother, bless her soul, let him walk all over her. My advice to her and to you will be the same.
Cut him off! Kick him out. Speak with the mothers of his children and take legal action. Have his wages garnished for shild support. Maybe get him into some sort of life planning/counselling therapy. I know as your son, you want to help him as much as possible. But he is the way he is because of the parents (and friends) that he had. Most likely, you gave him everything in the world growing up, and never expected much in return. This has allowed him to grow up thinking that "mommy will take care of me forever". Which I don't think you would like to do. Like I said, it's a touch cookie to bite into, but cutting him off will force him to grow up and take at least SOME respinsibility for his actions.
I am 21, have my own apartment with my lovely boyfriend (24). We have a 9 month old baby together and are saving for a house within 3 years. I think the idea here is that we made a plan. and put it into action.
It tough love doesn't appeal to you. try doing that. Make a plan with him and help him execute it. other than that. Im not sure what other options you have.
good luck :)