I reread it and I changed the penultimate line to include the specter. I thope that the added information will help readers solve the meaning of the bold lines, since the main POV is being asphyxiated and the other, unclear part/POV/subject is doing the strangling. But you would have to read it twice to get it.
I also removed some of periods to make the last section feel more stressful.
Lastly I removed the period from the first line to let it blend into the first stanza, indicating that the main POV and the specter are actually the same.
At the back of your mind
there is a specter.
Always stalking,
always talking.
Whispers of truths,
fires, famine, fear
too terrible to hear.
If I linger to listen,
It's spell will find me,
it's fear will bind me.
You see me everywhere.
It looms
in the rising spire,
over the forest fire.
It leers
from the dry riverbed,
where fish lie dead.
I'm getting closer now...
I'm pacing
heart racing.
All the distress
I can't express!
All the headlines
missed deadlines
records reached
tipping points breached.
And then, I strangle you!
the guilt
asphyxiating me
the specter
asphyxiating me.