Hi there. Most of us are from the U.S. and don't know about UK housing, but I assume there is no law that you can't force a 30 year old man, whether or not you gave birth to him, out of your home.
Now about the mayhem. In the U.S. you can get a restraining order. And many of us do. It is madness to give in to a 30 year old who abuses you just because he throws a huge toddler tantrum.
I don't know if you have legal options or not. Maybe call a lawyer for your mom? But...
Sounds like mom is unwilling to make him get out though and I don't think there are magic words to say to force her to realize she is being abused by son and stunting his growth. That he will not die and just may get a job if he spends a few nights on the street. He will not freeze to death or starve to death.
If Mom can't see this and your words fall on deaf ears, there is sadly not a thing you can do except back off/detach from the situation and keep living your own good life. We only have any control over one person....us.
Wishing you the best!
