The same thing happened to me although I don't recall ever being a "model" stay at home mom. The job wasn't for me. Although I love my kids and my home...it was a thankless job. I needed to feel like I was contributing to society in a positive way. I started crying all the time and sat around eating my heart's content until I went out in the world and found a job that I loved.
You have to get out and take care of yourself. Do fun things with friends, get your hair done and buy yourself a new outfit! I don't care what anyone says...moms come last and that won't change. We need to take a small part of our day just for us. Quiet meditation and prayer. Ask God what He wants you to do and discover His will for your life. And...take vitamin D!