I know where your comin from, my uncle was a tweaker for most of his adult life/ In and out of jail, out of my 23 years ive known him maybe 5 now. We cut contact, sick of loaning money and having him crash at my moms house, the grand parents, other brothers and sisters etc. And for awhile it looked like he was headed for either life in state or an early grave but something happened and he got his shit straight. Even If your friend started showing signs of improvement you still cant jump right back in tho, you might step right back into a role as an enabler. My uncle has had a career in electrical, has been clean gettin married and just closed on a house, so theres always hope. They just need to want it for themselves and be willing to go through what it takes to get it.