What does this poem mean? What does "happiness" mean? Is this poem well written?

The theme of this poem: two deadly emotions, I wanted to pester others, but I was involved.

Jealousy and despair are like two knives, trying to gnaw at your soul with them.

When it suddenly disappeared, I actually felt very relaxed and happy, never before.

When it appears again, it is in your heart! Slaughtering helpless me.