Hugs! I'm sorry you are feeling badly, but I'm glad that you are doing something about it. Has the weather been dreary where you live? It has been here and its really effected my mood. One thing I do daily to improve my mood, is to take a nice long walk. Its amazing what it does to level out my mood. If I'm stressed, I relax more. If I'm down, it gets my endorphins going.
Its got to be hard raising little ones alone, though. You are doing the right thing for your kids- but, still its not easy.