Lord, you did more for your friend than I would for most family members. I wouldn't consider you an asshole for having a sense of self preservation in the face of ruinous generosity... You're just trying to save yourself, but I'd say you should have started that process much earlier.

I wouldn't have done what you did in the first place personally: not for lack of love, or inability to provide for others, but because when a person knows someone else will cover their issues most people won't take them as seriously. Especially for young people fresh out on their own there's a tendency to assume the role of a child with older, or just better financially established friends and family members.

Need is the mother of motivation. If people don't really NEED to find a solution, then why would they? As long as you, or their parents, or someone is standing by to help then there's no need for them to face the music. If someone lives with a constant safety net they don't grow, they never really step up their game, and working more or harder isn't really a consideration. People in desperate situations are willing to do almost anything to survive, and there are a lot of possibilities in our current job market. There's also alternative living situations that they could have explored sooner that better suited their labored budget (her parents).

I think you've been an asshole to yourself essentially, but certainly not to this guy. The fact that he didn't immediately try to do everything in his power to find extra work, sell things, raise funds, or look for free living situations with family tells me he doesn't think as much about you as you do about him. Especially that cherry on the top bit about the TV. If I had found myself deeply endebted to a friend somehow I would try to look at a prize TV as a chance to repay the debt that I accrued.

Don't let his guilt dissuade your grief, that's a user's tactic as old as time. The guilt holds your anger over while they see if they can get a little more before you eventually wake up and realize you've been duped. You paid in more than you got out of this relationship by a long shot I'd wager, and honestly I pity you for letting it go this far. You should leave this thing be and see what he does without you shouting down his door for money. If he steps up his game and pays you back without any hounding or threats then maybe he was just in a stupid phase of his life, and he really does understand and appreciate what you've done. If that's the case then I think you can try and move forward with your friendship. If you don't hear from him for months, see him spending and living like everything was normal, and/or there's never any real attempt at a payback then please walk the hell away and realize you've been played.