A very bad day

It's a bad day.  I don't know why.  I wish I did, it'd sure make things a lot easier.  For me, my husband.  I have had to ask him to come home from work because I couldn't stop crying, feeling utterly miserable.  He wanted to know why I felt this way.  I wish I had the answer.  I have been battling depression for 6 or 7 years now, I have sought counselling, it was great, and it set me on a new path in my dull life.  I am a year away from graduating as a teacher now.  I take anti depressants.  Yet sometimes, I still feel like there is no point.  I've never felt suicidal, but in my down periods I find myself wondering, what is the point of life?  And then I feel ridiculous for not being able to simply enjoy the simple things that make life so wonderful.  My kids, my family, my pets.  I have a lot to be grateful for, so why, so often, do I find myself in such a dark place?  I hate being broken.