I hope that our few remaining friends Give up on trying to save us

Can we start by mentioning how all of Makoto's connections are involved with J? Before J, Makoto had no one. After, it was either J, demons that surround him, or were from his past. One of those demons was Kieran who was never able to never reach J, so he gave up and tried to somehow reach him through Makoto. Despite his attempts, Makoto's obsession with J ran far too deep to step between.

I hope we come up with a fail-safe plot To piss off the dumb few that forgave us

Another one of their "few remaining friends" was Datenshou who was a fool to fall for J. He would rather dismiss the atrocities both J and Makoto committed towards him in favor of that love. He was that dumb few that would forgive them because his self-hatred completely overshadowed any hatred he could have against them. Datenshou was the victim of their fail-safe plot — the permanent contract that forbid him from ever seeing those two again.

And I hope we hang on past the last exit I hope it's already too late

Their relationship was already doomed from the start. Their very first interactions — specifically all of vol. 1 — were vile to begin with and their bond was built up from contracts and desperation. "Last exit" in the context of the song refers to any final opportunities for redemption. In a literal sense within the manga, they've already crossed the threshold into Hell.

And I hope the junkyard a few blocks from here Someday burns down And I hope the rising black smoke carries me far away And I never come back to this town again

(I may be mistaken but) Like a parasite searching for a host, J was searching for someone that would be his key to the ultimate destruction of himself and his escape from Hell. All his actions to rise in the demon hierarchy as well as use Makoto involved the destruction of everyone around him. By his last breath, every step he took to reach it virtually damaged anyone and anything affected.

And I hope you die I hope we both die

Makoto would totally say that. J would probably too.

And I hope when you think of me years down the line You can't find one good thing to say And I'd hope that if I found the strength to walk out You'd stay the hell out of my way

This blog post is getting pretty long now so I'm skipping ahead.

Considering J seemed to have no shame in his treatment of Makoto or in leaving Makoto questioning whether or not he is loved, I doubt J expects Makoto to love him, at least not to a deep extent in the long run. Their complex relationship makes it hard for me to discern exactly what J wanted Makoto to leave with after he is gone. But he is certainly gone now, and Makoto has no way in changing that.

I am drowning There is no sign of land You are coming down with me Hand in unlovable hand

Both of them are at fault for the cycle of torment and abuse. Hand-in-hand, they pulled each other down to each others' misery.