1 year NC, 2 years after D&D, just passed him by and still i have so much Anger. Why?

As you can see I am 1 year nc and 2 years after d & d. It has taken me almost 2 years to get over him, after having a 9 year relationship (not married, no kids). To cut a very long story short, I thought I was over him, until today. I passed him by very closely in the car, he almost fell out of the window trying to see if it was me. I stared straight ahead, no expression at all. How do I feel now - so upset, I loved him so much and he tore me apart. I really thought the hurt had gone, why does it take so long to go away...I am so angry with myself for feeling this way, I was just starting to feel "normal" again and now everything comes flooding back.