They are

people who carry guns and people controlled by guns.

I

just

don't want to be the latter ever again.

Even if I got my revenge, I can't go back to my old life, but

I can make a new one.

Even now, I still can't handle blood.

As you said, I might not be suited for this industry, but

working to kill scum

frees me from the suffocation.

My weak past self, who couldn't save anyone

I feel I can separate myself from her...

But

you saved me, didn't you?