If you are in the middle of Shemoneh Esrei, and you hear Borchu while davening, you should stop, listen to the person saying Borchu and to the response (Baruch HaShem….), and should bow together with the responders UNLESS you are at the beginning or end of a berachah (excepting the first one, and modim).
HaShem’s first statement to Moshe Rabbeinu was–to behave appropriately in a mokom kodosh!!(Shemos 3:5). And you are still not careful about talking in Shul?