There seems to be two very different questions here: (1) “how can Heaven be considered a good place?” and (2) “how can Heaven coexist with this particular conception of Hell?” But the second question assumes a lot. For one, Heaven existing does not entail that Hell exists. So maybe there is a Heaven but no Hell. For another, maybe Hell—if it exists—isn’t a place of eternal torture. And lastly, being happy is not the same as thinking that everything is perfect. We live on a planet where terrible things happen all over and all of the time, yet we do not think that someone being happy immediately entails that they are indifferent to the suffering of others. So it also does not follow that being happy in Heaven necessarily entails some sort of callous psychopathy.