That was Tidus' dream. He never actually told his father how he felt about him which was a big part of the emotional impact of their meeting.

Tidus' tearful "I hate you" at the end really hammers home what I said earlier and what Tidus alluded to himself and that is he clung to all that resentment and all those memories because they kept his father alive in his heart.

Tidus loved Jecht in spite of everything.