The money wasn't a huge amount, nothing seriously damaging to our own finances, and my spouse and I also accepted the fact that it was possible he might not hold up his end of the bargain. No matter. We just wanted to offer a scrap of hope when he had none.
I think you might have to extend that approach to the rest of what you've given him (care, hospitality, support and so on). If he's very protective of himself and tends to isolate, then perhaps you're seeing a connection between you that he sees differently.
I don't mean to be unsympathetic, especially since you've been understandably hit hard by your friend's suicide. It's probably because I tend to be so alienated and protective of myself that I can imagine someone else feeling an emotional relationship with me that I don't express in return, for whatever reason.
I'm not seeing this as a friendship where give and take is to be expected pretty much equally. In that kind of friendship, what's given between two people is the same thing. That either stays at the level of socialising and companionship (I make the effort to spend time with you, and you make the effort to spend time with me) or it goes deeper (I support you, and you support me), but either way it's basically the same thing being reciprocated.
When things are much less equal, one person might feel they want to give to the other person because they're in a position to do that and they care. In that case, I think usual expectations of give and take no longer apply.
I imagine you don't feel that you made a bargain with him that you would support him as you have done and he would repay that with a particular degree of emotional attachment and trust. Having said that, you seem to have been holding that hope. I think you might have to stop weighing how much you've given him against how little he has given you in return. It doesn't sound likely that you'll ever be "repaid" on those terms.
You've done what you did out of goodness, kindness and sympathy. If he doesn't respond with the amount of vulnerability and sharing that you might hope for, then you still have the fact that you gave him help and support - whatever the outcome. There's no guarantee over how he'll respond. What he makes of it is up to him. Whether you choose to give any more is up to you. As with any gift.