The Mood Swing

[RSaba]

My heart is festooned with hate mail. "Festooned" means "adorned," generally in a cheery or holiday manner- maybe not quite what you meant. For a first line, this is a bit wordy. Maybe a simpler word would be better?
Painfully, I pluck each letter Pluck each letter... from where? From the pages? The paper?
in a desperate attempt to clear my name. That's good! With a few tweaks, this has the makings of an effective first stanza, and this last line will complete it nicely.

I am swaddled in discomfiture. One shouldn't need a dictionary to read a poem- we're looking for the emotion and the imagery, and a word like "discomfiture" just doesn't give you that. Often, the phrase that first comes to mind when you think of a feeling or image you want to portray will be the best one, whether it's simple or flowery.
I address my heart with a sinister resignation No need for "a" here.
while the radiant core of loving mocks me in its scarcity Perhaps "love" instead of "loving."
vanishing on a dime by spears of temperature or a critical stare. I'm sorry, but I don't know what this last line means. The first stanza is great, and the second one should expand upon the first. But this one doesn't have a central theme or image. I'm sure you know exactly what you're trying to convey- this piece certainly has emotion to it. But there are too many big words and uncertain symbols for me to understand that emotion. For instance, you said you addressed your heart. But to address something is to speak to it, and you never mentioned what said address was, only that it was resigned. This stanza has some cool phrases in it (I like "vanishing on a dime") but is muddy and needs reworking.

Time stretches, an abysmal yawn of untiring hopelessness,The idea of time stretching is great, but this line is once again too much. This is just a suggestion that still uses most of these words but in a way less cumbersome manner: "Time stretches, an abysmal, hopeless yawn..."
then snaps out of the vector of despair I don't think "vector" is the word you're looking for here. "Vortex?"
into a single rose. Time... turned into a rose? Disappeared into a rose? Ending with this simple phrase would be very moving and effective, if only it meant something. Keep this ending, these four words. I love them in themselves. But see if you can rework the rest of the stanza to make them mean something.

I know this seems like a lot of commenting, and I really hope it is helpful and not hindering. I can tell you have a lot to write about and many different ways to do so. But sometimes, wordiness is not the key to poetry. No more than one big word per sentence would be a good rule of thumb, or as you see fit. There are some really great lines and symbols in here that get swallowed up by those cumbersome phrases. Keep working on this one, I really like where it's going!
Take what you will from my suggestions, by the way. Everybody reads differently. And welcome!