Hi just-a-bill, and welcome. Punching bag sounds like a good description of you at the moment, though perhaps not stupid. Stress, exhaustion, depression, can impair judgment, concentration, memory, reflexes, so we're a lot more prone to accidents. Just what we need when we're already so low, but it's not stupidity.
Not that mine's been much help, but have you talked to your doctor?
I've found this site helpful -- hopefully you will too. As Daily Llama said, the forum's a safe place to open up and share what you're going through with people who are in a similar space. Write whatever comes to you -- there's no right or wrong.
Be kind to yourself, and good luck.