I Ask When, How and Why Did You Have Depression

I don't know if this qualifies as depression, but ever since being cheated on and left, I get really unhappy for a few days to the point of crying and calling myself pathetic and useless. Keep thinking of my ex even though she used to hit me. Think about contacting her and yelling at myself for it. I remind myself of positives in my life and it cheers me up, but only for a few minutes