First, I think it's great you are authentic and admit to not being fully detached. I think that's true of most of us here, we just don't admit to it always.
He feels guilty, and wants to assuage his own guilt by "making sure you are okay." Of course he can read you well and can tell things are not okay. It probably felt great to him to give you that hug.
But more importantly back to you... you don't need to provide any reasons to him. This is a boundary you are setting. "Please stop asking me if I'm okay" or "I do not want to talk with you, please stop asking." Short and sweet. The more you give reasons, the softer the boundary.
