Hi Lindalou and welcome to the forum. You're at the right place for support and encouragement for YOU.
I'm sorry about your son. I so understand the struggle in your mind and heart about setting a boundary with him, one that feels very stern and very hard.
I, too, had to set that same boundary with my son. He was homeless multiple times for months at a time over several years. It was very hard to live with.
However, this is what I have come to believe: adults must function at some level of self-support in this world. Other people can't live their lives for them, and it doesn't work to "shelter them in place". I did that, too, waiting for my son to grow up, to become more mature, less lazy, tolerating his pot smoking and drinking and flunking out of college, and being a slob and not working and being disrespectful. I thought he had "failure to launch" and all kinds of things I told myself that delayed the inevitable.
I finally had to understand that nothing changes if nothing changes. All of the "talks" in the world weren't going to change one single thing, unless he was ready to change his own behavior. I couldn't understand it for the life of me, his attitude, his whole way of living and thinking. He surely wasn't raise that way. What did I do wrong?
In my son's case, it was about addiction. He had become addicted to alcohol and pills and pot. You can trace all of it back to substance abuse, but I was in the dark about what was really going on for so long because he lied and lied and I believed him. I was very naive and wanted to believe him, because I loved him so much.
As I learned more about what was really going on, and the final straw came when he stole money out of my bank account (and lied about it of course, and for a while, I BELIEVED HIM!!!) and was stealing things from my house here where he lived to sell for drug money. You can't live in a house with someone who is stealing from you, it just doesn't work. I'm really glad that happened, looking back, because who knows how long I would have gone on like we were.
I kicked him out and it nearly killed me. But guess what? He survived. He learned how to navigate life on the streets, and in jail (for using and selling drugs) and this went on for a long long time, months and years. He is a survivor and there are a lot of resources available for homeless people (almost too many).
In time I learned more, thankfully, because I was distraught and extremely afraid for his life and safety, and truly felt he probably would die on the street.
But he didn't.
Finally, he got "scared straight" the last time he was in jail (he was in jail 8 or 9 times and we finally stopped being involved at all with jail, lawyers, court hearings, etc., all of it) he was told by the public defender that he would like go to state prison the next day for four years. My son said he lay awake all night scared to death.
That was his bottom, and who would ever have thought that he had to get to that point before he would start to work for change in his life.
I think there comes a time when we have to stop, as mothers. We have to stop, stand way back, set firm, kind and reasonable boundaries (without anger) and then learn how to stick to them. If we don't, our adult kids don't have a real chance to learn how to be adults, to learn how to navigate the real world, not on our terms, but on their terms.
Perhaps your son really does have disabilities. A lot of people have disabilities and they live as adults in the real world as best they can.
If you can, start thinking of it this way: Giving him the space to grow up and learn how to become an adult will be the greatest gift you can ever give him.
It will take tremendous self-discipline from you to not cave in..and if you do cave in...that's okay, just get back up and try again. We are only human.
Work to let go of the guilt, because it's a barrier to you and to him. You have done the best you could do, and once you learned differently, you worked hard to do differently. That's all anybody can do.
We're here for you during this struggle and this time of change. Please share with us openly. There is a lot of support, encouragement and compassion here. Hugs!