simple kind of wording is effective here, and the way it is presented is good as the poem unwraps, word by word phrase by phrase, just as the significant other in the speaker's life unwraps her "layer by layer/ tear by tear."
I liked the poem, but am not really a fan of the formatting. It reads well, but seems drawn-out to me. If this was your intention, then forgive me. If I were to re-format it, I would do it like this:
You were there
As my world fell apart
Your arms held me
As if trying to hold together my heart
Each word
Putting it back together
Piece by peace
You’ve always been the only one
To know
What’s hidden behind
These tombs in
my soul