JOEL - I can appreciate your thoughts and feelings. The basis of my opinion on this comes from the Doctrine and Covenants 76:86-87. Speaking of the telestial kingdom it says,

"These are they who receive not of his fulness in the eternal world, but of the Holy Spirit through the ministration of the terrestrial; And the terrestrial through the ministration of the celestial."

This has been interpreted by some to mean that those in the telestial world would be visited and ministered to only by those from the terrestrial world; the reasoning being that a personage of telestial glory could not abide the presence of a personage of Celestial glory. But even though a Celestial being might not be able to visit a telestial being, I would certainly think that you would be able to see them and know how they are doing. But they might not be able to see you.
Actually, this is mostly just educated speculation. No prophet or scripture I know of has specifically stated that a parent from the Celestial kingdom would not be able to visit their child in the telestial kingdom. No one but God Himself knows what we will or will not be able to do once we get there. So I wouldn't give up hope on that.
Also, right now you are thinking and feeling as a physical mortal being feels about his children. How do we know what we are going to feel or how we are going to feel as a Celestial immortal being? The Plan of Salvation is a plan of happiness. Our existance in the Celestial Kingdom will be a happy one. Somehow, even though one of our kids might be in hell, there will be no reason for us to feel any pain. We will know and understand and accept everything. Somehow everything we need to make us happy will exist within us and around us.
Also I wouldn't give up hope so soon on your kids yet. The time of our assignment of kingdoms is very far off in eternal future. They may still have another chance at accepting the gospel in the spirit world after they die.