Suffering has two sources.
Firstly, there are unbidden external events that interfere with my life or some department thereof. These are unavoidable and, in the Divine Economy (where nothing is wasted), therefore necessary.
Secondly, my feeling state is a consequence of my own willed thinking or behaviour. This is also necessary, on the same grounds. Error leads to fault, and fault leads to consequence, in the chain of cause and effect, without which the universe would be chaotic and meaningless.
My own mindset is involved in both: passively in the first case; actively in the second.
This means that suffering has a purpose: it reveals what requires change in me; it reveals idolatry: what I worship in the place of God.
Suffering is the chief actuating tool in the process of being saved (from alcoholism, from alanonism, from pride, from selfishness).
Anything that gets in the way of that—whether behavioural or chemical—blocks the process.
It is impossible to get well without accepting suffering as a necessary dynamic fact of human experience.