As someone else who I replied to said, I think it's about abuse, whether from a step-parent like me, parent, any relative or to a extent anyone. But this is my personal view...get ready it's LONG :P
I link it to the abuse that I suffered over 10 years ago that lasted around 7 years give or take, it links to the anger, fear and lonliness I felt, how I always thought about it and all the pain it caused, I cudn't ever escape it, and it tore me apart. (Until recently, when I started fighting back.)
"Nothing ever stops all these thoughtsAnd the pain attached to them"
This is basically what I was trying to say there, that I cudn't ever get over the pain of it.
"Sometimes I wonder why this is happeningIts like nothing I can do will distract me when"
I cudn't ever figure it out, why was it happening, what had I done to deserve it, all that kinda stuff, and nothing could take my mind off it for long.
"I think of how I shot myself in the back again'Cause from the infinite words I could say / IPut all the pain you gave to me on display / But didn'tRealize / Instead of setting it free / ITook what I hated and made it a part of me(It never goes away)"
This whole bit shows how when I tried to tell him, myself or anyone how I felt that I wasn't letting all the anger out like I thought I was, I was letting it take me over. The hate grew even stronger, and the desire and need for revenge did the same. I was making it a part of me, the hate and fear and rage was deciding who I was. (I've only recently started trying to change myself, after over 10 years, more than half my life)
"And nowYou've become a part of meYou'll always be right hereYou've become a part of meYou'll always be my fear"
This is all of what I said earlier, but shortened
"I can't separate myself from what I've done"
Again about the anger, fear and everything, I can't take the person I was away from what this has made me, the anger and everything has become a part of me...
"I've given up a part of meI've let myself become you"
...which leads to this, the fact that a part of me was gone, and tainted by the anger and fear and emotions that I felt.
"Hearing your name / The memories come back again"
I always thought about it but never really spoke about it, once I heard his name it hit even harder, I hate it but not as much.
"I remember when it started happeningI'd see you in every thought I had and then"
This bit I can't really explain, I always remembered what happened, but after he was gone I went numb, not thinking about anything, then one day it started, everything went back to him, why I'm so shy, why I am too protective if I let people close to me etc.
"The thoughts slowly found words attached to them"
I took these thoughts and linked them to my lonliness and fear and anger, so normal and even happy thoughts could hurt me.
"And I knew as they escaped away I wasCommitting myself to them / And every day IRegret saying those things / 'Cause now I see / That ITook what I hated and made it a part of me(It never goes away)"
This is the earlier points again, I have just started to regret everything I thought and said about him, it made the hold he had over me and my life stronger, even if he wasn't "there" anymore and didn't know. There's a strong chance he'll always be there, but I'm not letting the hate consume me, I'm gonna fight back and become myself again.
"Get away from meGimme my space back / You gotta just go"
This is what I've just started to realize, he terrorized my life for long enough, it's time for me to get my life back.
"Everything comes down to memories of you"
As the rest of what I've said most likely shows my life comes down to the same memories of this one person, it holds me back on everything I love doing, whether it's football, letting people get close to me and trusting them with my emotions or even just talking to people.
"I've kept it in but now I'm letting you knowI've let you go"
I've had enough, and I'm now fighting back...
"GET AWAY FROM ME"
...You will NOT ruin my life any longer, you won't get the satisfation. Kthxbi...without the thanks, just f*** off
I've let myself become youI've let myself become lost inside theseThoughts of youGiving up a part of meI've let myself become you
But I think you can interpret this song in anyway, and in as a big a level as you can personally link it to that way. That's why I love it, it's one of them songs that even if you have as strong a view as I do about it. You can still see how it could be linked to other things, such as what other people here have said.
If you read all that...WOW... have a internet cookie ^_^