*hugs* You're in a bad place mentally, and it's no fun.

I would strongly suggest seeing your doctor and asking for a referral to a therapist and a psychiatrist. There are drugs that, if the doctors decide to use them, might help you more than you realize.

I used affirmations - constant repetitions of phrases like "I am beautiful," "I am strong," "I am caring," "I am smart," etc. When you say it often enough, you begin to believe it. http://www.coping.org/growth/affirm.htm has an explanation of the principle and how to put it in action. People who tell you things to the opposite are not your friends and their opinion doesn't matter. Regardless of who they are, if they tell you that you are bad or unworthy, they are not your friends and you should not listen to them.

Join a support group. If you'd like, I know of a few forums dedicated to mental health issues - and what you're describing is not limited to submissives, it's something that anyone can experience. PM me and I'll give you the web address for a forum with very nice people who have been there, done that, and are more than willing to lend an ear and a shoulder.

As to what your Dom can do ... he should be understanding. He should not order you to "stop thinking that way" - it's impossible to just stop thinking that way, it requires a lot of work, and when you fail to stop thinking that way it increases the depression. "It's all in your head" is bad for me to hear, because it implies fault in my mental processes and minimizes the feelings that are, at that moment, very real, and if it makes you feel worse you should tell him that. Another thing that is bad for me when I'm in that state is play involving a lot of humiliation and name-calling, though my experience is not yours and your reaction may be different. It sounds to me like he's doing the best he can.

You mentioned that you get suicidal. Please, if that happens, call the number at http://www.suicidepreventionlifeline.org/ or some similar number. You shouldn't have to deal with that (and your Dom shouldn't leave you alone if he can help it). Those people are very caring and non-judgmental, and are available 24-7 to people in need.

I'm off the drugs now, and tea and chocolate are sufficient for taking away the blues when they come back. Your life can get better, and I hope you find something that works.