Had to respond JingleyJen - it sounds like a horrendous evening and a cry for help.
There are lots of ways that you can help yourself - I think that the first thing is to ask for help, to tell DH and any good friends and take it from there.
Phone the Samaritans, Go to the doctors, go to a therapist etc... Your depression is most likely linked to your childhood issues and when you can confront them you can confront your depression.
The legacy of my childhood was a huge amount of self hate, that just ate me up at every turn. All my life I had this underlying gnawing depression which never let me live my life.
I am in the process of recovery from self hate and depression - how?
I had the crisis - an unexpected pregnancy and knowing that I wasn't in the right emotional place to have another baby. Now I know that I wanted that baby but terminated the pregnancy.
First I read the books - toxic parents
Second I did this www.hoffmaninstitute.co.uk/
And recently I went to a kiniesologist/nutrionist and got some food supplements - after all these years I suddenly have levels of energy that I didn't know were possible.
I would say that as I write this I am calm and centered, I don't lose my temper with the kids, I don't expect DH to do things but appreciate it if he does, I am spending time making my home a nicer place to be in, I am looking after myself.....
When I killed my baby, I vowed that I would not let it eat me up with self loathing but would take it as a call to arms to sort myself out. And I hope that I have done so.
Maybe this is your crisis, your wake up call?
You teetered on the brink of a lonely, dark place tonight - but you can choose to confront it.
Good luck and big hugs