I have been in the situation you describe. It can feel awful and will for a while. Crypts offers a good outline of the many forms of help available to him. There is a path off of the street open to him, if he will make some effort to follow it. I went through this with a man I loved and with a brother, so I really do know what it's like. I know about the guilt part. That diminishes over time.

I remember saying to myself, "How can I enjoy getting into a warm bed at night with a full stomach, knowing "he" is wandering cold and hungry? One day I answered myself this way: "Yes, I am warm and and comfortable, and him not being so does not make me less warm or less comfortable. I am doing the things an adult has to do to have the necessities of life. He isn't, so he is distressed. That's sad, and I am sorry for him. I don't need to judge him. I leave that to God. But he makes choices that are irresponsible and he gets the natural consequences of those choices and those behaviors. That's how life works. My dinner and my warm bed are mine because I pay the dues to have them. I'm sorry for his pain, but I really don't have to feel his pain. It's not my pain."

There are reasons why he is as dysfunctional as he is. That's why I wouldn't judge. But life works a certain way. At some level, he simply will not accept the "rules" of how life works. He feels he should have an exemption. That's wrong thinking, but he's clinging to that thinking. He's an adult and has the right to make that choice.

You can get so wrapped up in pity that you decide, "I'm going to step in and protect him from all his wrong choices." You can ruin your own life that way. Or you can decide that his situation is a sad situation, but it's his, not yours. The world is full of suffering, some of it brought on by wrong behavior. And very innocent people doing all the right things get afflicted with awful suffering through no fault of their own. If you want to volunteer to help some worthy cause, do so. But don't make being someone's personal savior your cause. That just doesn't work out well.

You've had a learning experience. You got inappropriately involved in another human being's dysfunction. That's okay, but now you detach and move on. Life will feel sweet to you again in time. You won't feel his cold and hunger, unless you deliberately insist on dwelling on that. Don't.

This is a thing you can and will get over, if you stay detached and allow time to heal, as it will do.