Dill Mill Gayye S02 E10 Dr. Kirti Blames Herself

Dr. Kirti wants to know who gave propranolol to Dadu while Dr. Armaan suspects Dr. Ridhima. Dr. Shashank demands a confession from the culprit. Dr. Kirti says that she will probe the matter and blames herself for what has happened. Who is the culprit?