Hi Gal!
I have never "given up" on Dino, but I once had to give up the notion that I could stand having him around while he got good and ready to straighten up. Keeping yourself in the middle of the chaos is not support, it's collusion. Support is "you can do it", and it can be done over the safety of the telephone.
As to whether the trust can come back... I dunno. Dino is beginning a new phase... employed, housed and as far as I can tell, sober. I spend a lot of time with my eyes squinched and my hands clasped muttering "oh please, oh please, oh please....". Believing it's possible doesn't mean you don't need evidence of a sustained sort to believe that it has happened.
You can't save someone else from drowning if you're going down yourself. Don't kick yourself for getting out of the water.
Hugs,
Smoke