Hmm...
I'm not sure about "one-line poetry." If it exists at all, it would be extremely difficult to write. The reason is because not only every single word would have to have a purpose...every single syllable and sound would also have to have a purpose. There would literally be no room for mistakes.
But I'm just rambling now. Sorry.
xp
Anyway, your poem unfortunately does not maintain the structure of "every sound counts."
I think the first thing you should focus on {whether it be for this poem or a future one} is making abstract concepts tangible.
"shattered hearts" is a pretty abstract concept. How would you make that tangible? The word "shattered" itself is great. It gives a clear image. However, it becomes unclear when paired with "hearts." {I hope I'm making sense. I apologize if I'm not.} I'll try to explain. {There's no need to answer these questions. They're more for you to answer for yourself.} When you say "hearts," are you imagining the metaphorical sense or literal beating hearts? Now, you don't necessarily have to get rid of the phrase "shattered hearts." The words sound good together, but there needs to be something after them showing what that phrase means. Note that I said "showing" and not "telling."
wink
You could show through a simple phrase like, "shattered hearts, which spread like a thousand glass shards." People know what broken glass looks like. It isn't fun to be around, and it hurts to step in it. Do you get the overall idea?
"forgotten dreams" is similar. However, the phrasing doesn't sound as good as "shattered hearts," and it's even more abstract. Both words are abstract. What do you see when you think of things being "forgotten"? What do you see when you think of "dreams"? Now, put those things together. Show the reader what exactly "forgotten dreams" are.
I know this may seem like a lot to take in, but I simply want to help you improve. Perhaps you wrote this poem without the intent of editing it. Perhaps it was simply a poem to get it out of your system. That's fine. If you don't want to edit this poem, don't. I strongly recommend that you do, though. At the very least, I encourage you to take the advice given and apply it to your future writings. Remember: Show, don't tell. This makes abstract concepts relatable.
Good luck in your poetry!
biggrin