Lyric discussion by Yoshanuikabundi 

Cover art for This Is Goodbye lyrics by Killswitch Engage

Lyrics from the booklet for the special edition verbatim - there is at least one punctuation error that I've intentionally left in, and the lines are as they appear in the booklet:

This is my goodbye but please dont say a word
I don't exist I can't be heard
Each day's a new failure every trial is my master
Every step I gain  I only fall back faster
This is my goodbye but please don't try to stop me
There's nothing left there is nothing left

It's over please lay me to rest forgive me let me go
It's my choice so please lay me to rest forgive me let me go

I am no martyr this place overwhelms me
Once again I collapse I see no way to be free
I search for the answers is there no solution
I realize my reflection, my reflection is my demon

It's over please lay me to rest forgive me let me go
It's my choice so please lay me to rest forgive me let me go

It's my blasphemy hoping not to wake
Each day is the nightmare sleep is freedom
You gave but it was not enough
Your strength it was not enough, never enough 

It's over please lay me to rest forgive me let me go
It's my choice so please lay me to rest forgive me let me go

And with editing for more song-like line breaks and correct grammar:

This is my goodbye
This is my goodbye

This is my goodbye
But please don't say a word
I don't exist 
I can't be heard
Each day's a new failure
Every trial is my master
Every step I gain 
I only fall back faster

This is my goodbye 
But please don't try to stop me
There's nothing left there is nothing left

It's over 
Please lay me to rest 
Forgive me, let me go

It's my choice 
So please lay me to rest
Forgive me, let me go

I am no martyr, this place overwhelms me
Once again I collapse 
I see no way to be free
I search for the answers 
Is there no solution
I realise my reflection, my reflection is my demon

It's over 
Please lay me to rest 
Forgive me, let me go

It's my choice 
So please lay me to rest
Forgive me, let me go

It's my blasphemy 
Hoping not to wake
Each day is the nightmare 
Sleep is freedom
You gave
But it was not enough
Your strength 
It was not enough
Never enough 

It's over 
Please lay me to rest 
Forgive me, let me go

It's my choice 
So please lay me to rest
Forgive me, let me go

I don't have time for a particularly in depth analysis right now, but I wanted to say now that I think this song may be about euthanasia, and the sufferer trying to convince his loved ones to 'pull the plug'. Suicide seemed close, but I certainly do NOT think this song is about a breakup.

I might go a bit more in-depth tomorrow...