But Cloud may have pushed his guilt issues to one side to defeat Sephiroth, and replaced them temporarily with vengeance. He wanted to defeat Sephiroth for many reasons, but perhaps one of the biggest reasons was to avenge Aerith's and Zack's lives (obviously saving the world was high up there, and his mum's life, but trying to focus it a bit).

The moment he defeated Sephiroth, he realised nothing had changed. Avenging their lives didn't bring anyone back from the dead. And now he lacked a purpose, so all he was able to do was look at his problems. He never confronted the majority of the issues, like the burning down of Nibelheim, or Aerith's death, because he was basically unable to do so, due to the fact that he had to stop Sephiroth. Now, that was all he could do.

It's kind of how some people deal with trauma by digging themselves into so much work that they can't think about it. Cloud did that with Sephiroth, but the moment that was done, he had little left to do. And yes, he used his disease as an excuse to get away from Tifa, because he didn't want to be around her as he felt a complete failure.

I think the speech between Vincent and Cloud was supposed to illustrate how Cloud had followed onto Vincent's path. Vincent isolated himself completely from the world, so he could brood on his failure to protect someone close to him. He was also looking for forgiveness and redemption from someone who was dead. Likewise, Cloud felt responsible for Aerith's death, and wanted to brood on his failure.

So, I guess that means Cloud is emo. But I think he had a right to feel emo, based on the original events. And he has other flaws, such as the immense lack of self-confidence and self-hatred. But that's what makes him quite interesting.