Kitt's right about seeking help. Her advice is sound and good. She's a great person to listen to. She's already showed me some things I should be thinking about with my depression and anxiety, and they have helped, even if in only small ways, and I've only been a member here for a week or so. So please listen to Kitt - do whatever you can to talk to a professional, doctor, or counselor about the way you are feeling.
The second thing you can do is to continue to come to this forum. Most folks here have felt the same things you are feeling, have had the same thoughts, have had the same trauma. We really do understand what you are going through because we have gone through and are going through those same things now.
Talk things out here if you have no other place to go. You will know you are being listened to and heard. Members will respond with posts that may help you sort things out some.
It would be great if one could promise an overnight cure for what you are feeling, but that just isn't how it works. So that is all the reason more for you to be here and vent what you need to vent. Just about everything you mentioned in your post - I have felt and experienced. When it happens it makes me not want to go on, but you know, I'll be darned if I'm going to give into that. There are good days and bad, but I am not going to let depression win.
You came to the right place. Please stay on. I would be more than willing to talk with you any time you needed to talk.