Sure it is mental anguish, it does not have to be a permanent state. Things happen in our lives that are hurtful, painful, stressful, things we can't control, you made will try to make sense out it and can't and you will feel mental anguish and probably some depression.
The bottom line is to not focus on it as something that will harm you forever. It is like falling down and hurting your knee, of course you will feel pain, that's the same thing as the mind. If you encounter an unpleasant event, of course it will cause mental anguish. It is permanent? Has it harmed you on a constant basis? Is it impeding your ability to function in everyday life? Those are much larger questions that now touch upon something a little bit more harmful, but mental anguish in itself is not a bad thing, it is a human thing, it's a reaction.