Generally speaking, "Buddhism is like Christianity" - in the sense that it has many different schools and sects that have their own practices and disagree on interpretations.
However, when it comes to suffering vs pain, most Buddhist nominations should agree with that statement. In fact I suspect this entire idea was taken by DBT from Buddhism. Suffering is not the best word for dukkha
though, hence your confusion/resistance. Dukkha
is the painful feeling we have when things are wrong and we can't do much about it.
If that makes you feel better, here is the same phrase in some alternative renditions:
'Pain is inevitable. Unhappiness is optional.'
'Pain is inevitablea part of life. Frustration is optionalup to you.'
The idea is that external circumstances are not in our control, even our state of mind is not always in our control... but our attitude - our deep inner peace - is entirely up to us. Even if we're in pain and dying, we can be at peace an die gracefully, can't we? Let alone when we have normal difficulties.
This idea is slightly more palatable than telling someone their suffering is self-inflicted, but even this may be hard to accept for someone used to being in the victim consciousness. We're very used to explaining our unhappiness in terms of the circumstances. But as my Zen Master used to say, keeping our mind clean from unhappiness is like keeping our kitchen clean from the cockroaches. It is entirely our responsibility. In fact, rather than feeling pity for ourselves for being unhappy - we should be ashamed of not keeping our "kitchen" clean.
This is Emotional Intelligence 101, and a lot of it comes from Buddhism. Consider the Four Right Efforts:
... monks, you should apply effort toward:
- non-arising of bad, pathological states of mind that have not yet arisen.
- abandonment of bad, pathological states of mind that have arisen.
- arising of wholesome states of mind that have not yet arisen.
- maintenance and development of wholesome states of mind that have arisen.
Even the Noble Truth itself is a form of the same principle. The core idea is that dukkha
(unhappiness, frustration) comes from an inner conflict. Conflict between how things "should be" and how they "are" - both sides modeled by our mind. The Buddhist path leads a person to the ultimate state of peace called "suchness" (tathata) - the state when "is" and "should" is no longer in conflict. This is achieved through a combination of objective (behavioral) changes in one's lifestyle and subjective (attitude) changes in one's psyche.
Buddhist Nirvana is the culmination of this path from conflict to suchness.