Very good! I love it!

What I think you need to do though is take out the commas in the middle of the phrases and semi-colon. It makes it kind of choppy, and a poem is suppose to be smooth and seamless.
So instead of :
It used to be so fun, so new,
But now it is the deadliest poison
And it is killing me slowly
I need a quick fix, and,
I can’t help but remember,
The way we once laughed.

Try:
It used to be so fun and new,
But now it is the deadliest poison
And it is killing me slowly
I need a quick fix and,
I can’t help but remember,
The way we once laughed.

That way you have a better flow. In my opinion (this may just be me... who knows?) a poem should be like a song- smooth, good transit and pleasant to 'hear' in your mind. If it has a lot of punctuation it makes it jerky, and that's not really appealing (unless we're talking Will Shatner here.)
Hope I helped you! Again amazing poem!!