The realization hit Kokichi pretty hard. He was silent for a moment as his mind went back and forth between denying it and accepting it. He stood there, shaking with tears forming in his eyes. He wanted to argue against it, but he knew that everything that Kiibo said was the truth. He knew that he was going to die at one point or another, and now was the time for him to accept it.
"Kiiboy…I…I'm sorry…" Kokichi cried, tears freely falling down his face.
He said nothing else. All he told Kiibo was that he was sorry. He was sorry that he was going to die. He felt like it was all his fault, that he could've prevented this by taking better care of himself. He never knew that it was a genetic condition that was killing him. He felt incredibly guilty in that moment as he stood there and sobbed.
It's all my fault…! I could've prevented this…! he told himself as he stood, trembling, in Kiibo's arms. Kiiboy's gonna lose the one person he loves, and it's my fault…! I'm just letting myself die like the idiot that I am…! Kiiboy…I am so sorry… I don't wanna die…and I'm sorry that I have to be dying… I could have done better if I tried…but I didn't…
As he continued thinking, he began to full on sob. He couldn't help it. He was terrified of death, and he felt guilty for what happened. He was shaking a lot as he held onto Kiibo, silent aside from his sobs. He couldn't handle it all, but he accepted it.