So confused

I had a hard weekend; trouble sleeping and keeping him out of my mind. Still NC and going forward but having moments of confusion. I seem able to reel myself back in to the reality of the situation, but I'm finding that I'm having trouble making the simplest of decisions be it personal or work. For the past several days, I have been doubting myself and feeling very frustrated. The doubt he instilled in me seems to be consuming me in other areas of my life.