Soberred, it's OK to feel bad. You are going through rough times, one month sober. Your feelings are all over the place, and that's to be expected. What isn't okay is beating yourself up for feeling sad.
Feel sad, but don't despair about feeling down, because despair is the crack through which your addiction will sneak in.
Sleep, read sad poetry, listen to Janis Ian records...all good activities when you are blue.