You're gonna be a miserable fuck who's past trauma (probably not the right word) will be reopened, catch up to you and will break you in ways you knew you were expecting but not this soon. And the things that caused you to become like this, is those people. so I'd suggest either to kill yourself like you've always been thinking or stay away from the triggers. Yes, you're gonna break that promise you made to yourself but if it mean't saving yourself from becoming like the piece of shit you see right now, then it'd be worth it.

You don't want to be more miserable than you are right now, trust me, if anything, I wish I could holdback all my feelings right now like you. I know your holding them back suppressing them and that caused you to be in a state where you don't care about people, you can't think of any reason to make you want to remain here and just letting life and everything around phase past you, as if you were just dead on the inside.

Like I said, the people you will become friends with because of the comic/manga club will introduce you to people who will become the triggers to reopening that past promise and trauma. Don't bother with them, just give them the message you have no intentions to be around them.

And I'm sorry for what you're gonna have to do next and for what you might become because of the actions you will take next. But promise me this, you will always remember that you tried your best to fix everything, and don't ever holdback because you justify it as "I need to be strong for the people I care about, to protect them from myself." The world doesn't owe you anything kid, that means even though you are protecting these people from yourself, that doesn't mean they owe you squat, which gives you all the more reason to either kill yourself, stay in your melancholy state and not bother with people or don't holdback and just shout, scream, cry and wish everything could have been better for yourself if you never got involved with her in the first place.