In sonic epilogue why did tails killed sonic

Tails killed Sonic in self-defence because when Snively injected that formula into
Sonic's arm, it turned Sonic evil. If Tails hadn't have stabbed Sonic, he would have been choked to death, so it was a lose-lose situation, anyway. And I'm sure that the last thing Tails wanted to do was kill his best friend.

I'm pretty sure that Tails killed Sonic because he had to. Sonic is the fastest thing alive, he always wins, and he can become Super Sonic if he has the Chaos Emeralds. Tails had to kill Sonic because if Sonic is a bad guy then everyone may as well kill themselves. No, he didn't want to, but Tails can't technically be choked, as he has no neck.