ERJ 175 Flight Attendant reported being distracted and engaged the main cabin door handle; resulting in an inadvertent escape slide deployment.

Narrative

I was the forward FA responsible for the Main Cabin Door (MCD) opening and closing. I became distracted mentally when the passenger stated she was going home to take care of her mother who had cancer. It invoked memories of me traveling to take care of my mother who was dying of cancer; and I began to have intrusive memories and sadness; I began the disarming procedures and cross check and when I finished the cross check I had a memory of my mother and proceeded to lift the MCD handle without thinking about the procedure that the Customer Service Agent (CSA) was responsible for opening the door. I stopped engaging the MCD handle and the CSA attempted to open the door and I informed her that the slide was deploying.Cause: I was mentally distracted before engaging the door handle and didn't not revisit stop drop review after my mental distraction; to review my next steps.Suggestions: I should have taken a deep breath to clear my mind and done a stop drop review when I had a mental distraction. I think retraining on ERJ MCD for FWD FA will help; and flying the ERJ monthly so I don't lose my skill sets.