It's nice to feel needed, but not to have a needy person around. Carry on as you would before he left, if you find yourself in the same room as him most of the time, move on, go out and do something you like. I can only think of one reason he'd think you dont' care, if you openly ignore him, otherwise be supportive without being overwhelming, do ask about his day but also let him do his thing, whatever it is he likes to do to relax, you know what he likes.
Again, remember how confident you were when you were dating, be that attractive person again. DOn't over analize things, I tend to do that too, or read too much into stuff.
Be not afraid...I will repay you for the years the locusts have eaten Joel2
30something 2kids survivor of S, MLC, A, D I have peace in my heart, at last.