The nature of hell or eternal torment, as a teaching of the Church, inasmuch as what has been revealed is clear, has many aspects--the outer darkness, the weeping and gnashing of teeth, the undying worm, etc.--which are understood, primarily I think, as spiritual, although the physical dimension is not lost since then man will be reunited, body and soul.
Of course, since God is everywhere present and filling all things, there is no place where he is not. But, will the "damned" be in his presence, that is to say, at his throne, at least according to the language of the Scripture and hymnography? I don't think so. Will it be God's presence, per se, or God's love for them which will be their primary tormentor? I'm not all that convinced, since their spiritual eyes will be opened and their conscience, which they did not heed in this life, will not cease to reproach them in eternity.
Every evil deed that was done, ever good deed that was not done, the person will suffer over noetically, not through God's action, per se, but because now the "damned" cannot distract themselves with sin, cannot justify themselves, can no longer ignore or kill their consciences.
There has to be a time when this world's parameters--its changes and effemerality--end, and the eternity dawns for God's creatures whom he created to be eternal. Man was created for eternity. Destruction out of compassion--I can think of no precedent for this. On earth, we call it euthanasia and murder and condemn it severely.
The demons certainly knew their fate would be eternal torment when they rebelled against God because of pride. That they might not be alone, and in an attempt to justify themselves, they tempt man and goad him into sin and rebellion. But man is a free actor in this, as in all things. He also has free will to choose between good and evil. God gave him a conscience and various gifts, as well as his divine aid, and no one will be able to accuse him of unjust judgment should eternal torment be the lot of any man.
I prefer to believe that eternal torment is a very real possibility, especially since the way to life is narrow and difficult, even for the just. I do not know if I shall be numbered among the saints, with those who are saved. I put my hope in the mercy of God. I commend everyone to God's mercy, trusting that his judgment is true and there is no unrighteousness in him, and that everything he does is out of his love for mankind. I pray that God would save every man, every sinner, because I am the chief of sinners, and if they are not saved, where does that leave me? But I put my hope only in God and what he has promised and revealed, and universal salvation is not something, to my knowledge, that he has ever promised or revealed. It is not the teaching of the Church.
I prefer the standpoint of expecting torment and being pleasantly surprised and better able to glorify God, rather than of expecting universal redemption and being disappointed, and less able to glorify God because I thought I understood him, but was proved wrong. We only have faith in what has been revealed to us by God to go on, not our personal understandings of how we think God should be or how we would like him to be.