What's the OST playing in "No Regrets" OVA when Levi is fighting with Erwin? The OST appears in No Regrets OVA when Levi fights Erwin and Mike and is played exactly when Erwin comes in.
I believe it's "So Ist Es Immer". It appears when


   Farlan and Isabel died.


It appears to be telling Levi his choice is wrong.