Vicious Cycle
noun
You already know that 循環 means "circulation" or "cycle," so adding bad to that makes it a vicious cycle.
あくじゅんかん
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
まずは、あなたの心の悪循環を断ち切ることが大切です。
First of all, it’s important to cut off the vicious cycle in your heart.