You don't have to respond, but I would...I would say my day was okay and leave it at that. He doesn't realize why you were so upset because mlcers' empathy chip is broken and he could also be fishing to find out what was wrong. They are clueless how to speak directly to us during their crisis. They go all around Robin Hood's barn to get to the point.
If you don't feel well, so be it. No one says you have to be the happy chipper birdie all of the time. This stuff is hard and yes, it's emotionally challenging s well. You are going to have good and bad days. If you aren't feeling well or up to the BS, be honest and tell people it's not the best day and leave it at that.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.