My heart goes out to you. I've been going through the same thing with my son and he's 32 yrs old. Been to prison at 18 off and on for the last 15 years. He's been out for around 4 yrs. I think he would have been dead a long time ago had he not been in prison.
He lives an hour from me in a house that his dad pays for (he moved out as he couldn't take it and he's an A himself). He continues to pay the mortgage (it's a dump in a bad area), he pays the lights, heat, and cell phone. Son works off and on but can't get along with people. He's working now ... and I cringe to tell you that I loaned him $1200 for truck tires. Then he lost his job .. got another one. But for how long? I'll never see it.
He gets drunk and calls everyone at all hours of the night. I've finally blocked him from my home phone but haven't blocked my cell phone as I'm on someone's plan but it ends in September. I have around 8 horrible texts that he left as i am trying not to give him any more money. I am a verbally abused mom ... the last text went something like "don't you ever call me again you dumb f'ing b. As far as I'm concerned you are nothing to me. U are ignorant and the most neurotic ____. Don't u ever contact me again, you f'ing b. I want nothing to do with you ever again". Haven't heard from him for a week. He'll eventually call and act like anything is wrong. If i bring it up he'll say "i was just mad or drunk, or whatever".
I never call him ... he always calls me. I am not a weak person and there is no way I'd put up with this from someone else. I divorced his dad 20 some years ago because of alcohol. At least his dad is a functioning drunk. Never in a million years would I have thought I would have a son who would treat me like this. Around 5 yrs ago, he came to me and my current husband, when drunk, and let out a secret he'd had for a long time - he was molested when he was really young, by an older neighbor kid. Someone we trusted, who would take him fishing, etc, and that has contributed to him being messed up. But he won't get help. I made him an appt with Salvation Army's Harbor Lights for an initial evaluation .... he was going to go but backed out at the last minute saying he wasn't going to believe in "their God".
I have called many a times to have the police check on him - a "well check" and you could do that with your daughter. One time, they actually took him to be evaluated and they were supposed to hold him for 3 days. They let him out the next day and said nothing was wrong with him. Just has a nutty mom.
I'm trying my best to not think about him ... he's already told me he won't stop until he decides to stop. Until then, I have to let go. Geez, this shouldn't be so hard.
You are not alone.