Aw, Kathy. Even Glass Half Full Girl is allowed to have a crappy day - allow yourself that. Then pick yourself up and get back on the happy train :)
I think you might have to embrace the meltdown (like the grieving process), and you might come out the other side with a half full glass. I feel better after a meltdown... and then it happens again but at least I have some good days. :)
I can so relate. Some days are easier than other, but we must hang in there!