Sigh.... If it was me, were I in his shoes as the MC, to protect the secret of Felice's existence, all the more reason to make a huge statement with an action:
- Showing how overpowered I am, so much that I can't be subjugated by the entire school even, followed by
- Should there be anyone trying to mess with me or anyone or anything important to me, he/she will get the very same treatment he/she was trying to do to me or the one I consider important to me, nothing more and nothing less
By doing that, I am actually making negotiation with these arseholes on the same level as them. And also making a point to them that with every actions, there will be consequences, so that they won't be messing with me, as I am not someone they should be messing around with, what with the power I have. So they should give me respect and they should just mind their own business if they don't want problem.
Also, with regards to Felice's existence, I could always lie about it and say that I killed her to cover the fact that she is still there, couldn't I? It's much safer that way. As for the proof of slaying.... Hmmm.... Maybe it could be said that the battle turned into a battle of attrition and in the end I endured it until she died of exhaustion, so I won because of that. I am still stronger than her and I actually won against her that way?
(Btw, I am using "I" here because I am talking as the MC, putting myself in his shoes)