A very upsetting poem, the pain is evident in the words, if you're writing from experience, i feel for you, if it's fiction, well done on capturing the emotions.
"Like icebergs did to titanic"
Titanic should be capital T as it is a name.
"The way you played that song
The day you made me cry "
This stanza is very heartfelt, truely captures the mood, i would change the second 'the' to 'that' to try avoid repetition that can put the flow off.
"I couldn't take it anymore
I just felt my whole body crumble"
Once again, captures the emotions perfectly, i would maybe change the second line to something like "Felt my whole body start to crumble' just to avoid repetition again but it works either way.
"And the pain an ache that spread"
Spreads with an 's'?
"All the way to my toes till I was numb and fearless
So when your anger rushes like flood into me"
I loved these two line, you can almost see the force of the anger crashing through. Althought 'rushes like flood' doesn't make too much sense, maybe 'flood-like' would be better?
"I wish to take refuge in my knowing
That there's so much more I love in you, than what I don't
That I can never ever make it up to you
How much you've given"
I loved this part, it's so true the part about loving more than you don't. Really stuck a chord with me.
"But I'll try till my blood boils
Till there's nothing left and even plastic flowers have faded
For you I'd abandon any ship knowing I won't sink
You'll be my life raft in this sea of mess I'm drowning in"
Wouldn't change a thing. Perfection! I loved the plastic flowers. An excellent way of showing the length of time
"All I want is to have you breathing next to me
I'll figure out the rest along the way"
A fitting finish, truely sums up the poem brilliantly.
Overall, i think you have an amazing piece of work here and with a few tweaking here and there you have a winner!