berachot

Question

Kavod Harav, If someone does an aveirah that if done not through sin (i.e. eating) would require a beracho, does he make a berocho, basically to unconfuse things, if someone eats tereif, and then he feels bad about it right after, or not, if he makes a beracho achrono is it a berocho levatalah? is it a mitzvah habah baverira? Thank You. Jaob