Biggest mistake

I made a promise to myself
I wont let her down
Till I lost my way
And needed only her help
Then I saw her fall again
Down to the ground
Its all over, and I hurt her
When I had told her
She mattered more
More than the world

I told her those three words
I love you said it all
Then I threw it away
Rebuilt those walls
And now sorry doesn't cut it
I cant get rid of it
She had meant everything
But I couldn't handle it

These cuts on my wrists
They're bleeding all over
Her hearts shattered again
I cant even hold her
To say it'll be OK
And that Ill always be there
Cuz I was selfish
So now she feels hopeless
Cuz I thought
It would make it OK
It didn't even last a day
She was my best kept secret
And my biggest mistake