Was this poem meant to have no punctuation? If it's for the purpose of adding ambiguity, then make it clearer perhaps? It's just that poems without commas are hard to read cause we naturally read fast when there's no commas there.

'After everything that he did to me, thought I'd never recover
Feeling the world had ended, for I could only ever love him
Someone who made me euphoric had left me to suffer
That's how I felt until that day when you walked in'

I liked the use of assonance here, none specific rhyme works well, it makes for a better flow, and it doesn't feel forced. Perhaps add a comma after 'felt', as this will make the meter feel more sharp.

'Noticing that slowly this broken heart was mending
Without warning you were taking piece by piece
Slowly putting all those shards together again
All that hurt and pain, you became it's release'

The second line was the strongest, although I was confused by the last line. Did you mean that the person released your pain as in made you feel the pain, or he released it as in he cleansed the pain?

'I'd sworn to myself never to love again
Adamant that I was going to lock my heart away
I'd finally tired of empty days and sleepless nights
Didn't want to be that heart broken cliche'

This stanza was strong and heartfelt and it felt honest and raw, which is what you want a poem like this to feel like, so it was successful in that. Again though, the last line could be reworded. I guess that you're saying that you didn't want to be 'just another' heartbroken girl? If so, you could reword it because I thought the word cliche only related to words, ideas and expressions. Unless I'm reading into this wrong, then I apologise.

The fourth and fifth stanzas are the most strongest in how they deal with the narrators feelings, and the somewhat happier ending dosen't undermine the preceedings, so well done for that. A very good write, with some tweaks it could be a greater poem.