The ice cream comment was the most heartbreaking part of the scene for me. The line definitely sounds really silly, but I think it perfectly showcases Roxas' innocence and his intense desire to connect with others even though he doesn't quite understand how. The very definition of 'friend' he learned from Axel, someone that you share ice cream with. With whatever form of a heart he had at that point it was the only way he could begin to grasp the concept of friendship, and he held onto it with so much sincerity.
That being said, while I definitely cried during that scene, I think Aqua affected me the most emotionally in the long term. The way she does whatever she thinks is truly best for her friends, even if it means making massive sacrifices. Terra and Ven never really understand just how much she cares for them and what she does for them. Calling her awful was way outta line, Ven!