living with a sibling that is an addict, what would you do?

[Invisigoth]

"there is no handbook given to families of addicts"--actually there is. it's called Al Anon or Nar Anon. you'll learn about addiction & how not to enable your brother. you'll learn how to set limits with him & how to enforce those limits.

until you're prepared to let him fall flat on his face & hit his personal rock bottom, he has no reason to improve.

right now, you're not really helping. you're still too busy trying to protect him from the consequences of his addictions.

go to the meetings (they're free) & learn how you can really help him.

as for what I'd do:
write up a contract for him that spells out the conditions that will allow him to remain in your home. make it clear that if he violates those conditions then he has to leave.

if he leaves, you'll need to change your locks so that you're sure he doesn't have a key to get into your home when you're not there.

don't worry about him being homeless & not having any where to go. you can point him in the direction of a local shelter or he'll find someone else to take advantage of or he'll straighten up.