I think that you've had some good advise so far. Especially from poetdowns. It's hard for us to help her, when we are not in direct contact with her. BUT... you are here and we can help you. I can understand why you feel you are 'talking about her behind her back'. It may help you to think that you are really helping yourself. Understanding what is happening may help you bear it or 'manage' things better.
Poetdowns had 2 points I felt were especially good.
1. Dr's will treat her according to their training. You will need to train yourself in all areas. A psychiatrist WILL want to medicate her, a psychologist WILL want her in therapy, GP's may send her to other specialists and so on. You may find she needs to be in therapy and on medication. Then you'll need to research the medication etc. Learn all you can so you understand her. BEWARE: Do not analyse her or tell her what to do. She will not appreciate it.
2. It's better for children to understand what's going on around them. Find a way to help her communicate in a way they'll understand... a code.
You may need to find a way to communicate her degree of anger to them. 'Mummy's as angry as a grape' , 'Mummy's as angry as a grapefruit' or 'Mummy's as angry as a watermelon... you better leave.'
Teach her to postpone activities that she can't deal with. Your children will prefer 'I'm really angry right now, I'll read you a book after dinner.' to 'I SAID, GO AWAY' (note:they will prefer a time so they know it will happen) and they'll understand if mummy has a timeout.
If there are any behaviours in your children that can be redirected that will help. For example 'whining' it is not naughty or bad but, it IS annoying. If this is something that sets her off, it may help to tell your child, 'Can you hear how I'm talking? You ask like me and then we'll see'
I would add to this good advise by saying.
1. Help her find passion - with you or some other activity. Seperate her from the house and the children. Take her away for 2 nights. Do not bother with one night, the first day will be spent getting there and then you'll wake up thinking about getting home. Leave early the first day take your time. You'll feel like you've been gone for a week and you'll meet the person you fell in love with. You may say that you can't afford it, but trust me, it'll be more expensive if she does leaves you.
Help her rekindle a lost passion. Find out the things she loved to do in high school, find out things she always wanted to try, who did she want to be?
I wish you the best of luck and I'd love to hear back from you. When you apologized for intruding you were mistaken. There was no intrusion. You have begun a conversation and in any conversation questions, disagreements and/or updates are welcomed... even hoped for.
P.S how many and how old are your children?