The question ultimately is was this part of Hashem’s plan? Can something happen that isn’t part of Hashem’s plan?
I saw a vort recently (can’t remember where) that גם זו לטובה means that the only reason you’re viewing it as bad is because you don’t see the full picture, if you did you would see a masterpiece and ultimately this “bad thing” was really good
To joe’s question of “ Does that make the Holocaust a good thing?” I have heard that if the holocaust didn’t happen there would have been so much intermarriage that we wouldn’t be able to recover as a nation, so in some aspects it was “good” (I apologize to the posters that had ancestors that perished in the holocaust I’m not trying to make hitler yms a good person, nor what he did was a good action, but it is all in Hashem’s plan)