Who do you feel sorry for?

Probably Boromir, because he repented his sins, realised that he had brought everything to the brink of wreck and ruin, because he was unable to fight or control his desire for the ring. He was a noble man, powerful and strong, who was corrupted by the power of the ring, and could not do anything about it.

As Gandalf said, (paraphrasing) alas for Boromir....it is good that I foreced Elrond to allow Merry and Pipin to come along, at least for Boromier's sake.

Every time I read the breaking of the fellowship chapter a tear comes to my eye, as when I watch that scene in the movie.

I feel a different kind of pity and sorrow for Gollum and for Frodo, but they (at least in my mind) did not ever realise that what they had just done could have resulted in the death of everyone they loved, subjection to slavery of their people and betrayal of their friends.