Will people in Heaven be aware of friends/family that aren't there - that were sent to Hell? Wouldn't this cause sadness?

Since we will be the same people we are today and will remember our lives here in this age, even being judged for our deeds (2 Corinthians 5:10) and everything coming to light (Luke 8:17), it would seem that we will be aware of friends and family that are in hell. We will even have a part in judging the world (1 Corinthians 6:3). And I suppose we will be sad and grieve. Yet God will wipe every tear from our eyes.. (Revelation 31:4) He will have the ability to return us to joy even in such a great loss.

-- Dave