I think that it is incredibly sad that your 'friend' disappeared on you when you needed his support - especially after everything you'd done for him.
I do think it's a delicate balance. People who have a tough time can have ups and downs for a long time after whatever the event was - and we can't expect to put a time-limit on feelings... but I think you hit the nail on the head- as soon as it becomes a victim complex that can be when all the support and compassion in the world can end up disappearing into a void.
But even in the depths of difficulty, positive people have that seed in their soul.
E x