I think a lot of us experience this too. As we crawl into our comfortable beds with warm blankets our hearts ache with the sadness of what we wish could "be" for our children.
I pray for the homeless all the time but I also pray for the mothers, fathers and loved ones who feel such sadness because their children are on the streets in some capacity.
I'll continue to pray for you and your son. But take it one day at a time, if need be, one hour at a time.