I wish I had the courage to kill myself is something I told myself all the time when I was really low. I don't know if this will help, but you need to close your eyes and remember that courage will not come from ending your life. Courage is dusting yourself down and choosing to live.
Has your DH told you he wants to leave? Does he still love you, tell you he loves you? From your thread, it seems he is not at all supportive, but possibly your mind may be blocking out the support you are getting.
If things are not working between you and DH, then if you did die, your life insurance is there for your DD. And if things between you two are working, what use is money to him when his wife has just killed herself?
I was 15 years old, telling myself that I was ready to die, that everyone would be so much better off/happier without me in the world. I'm 18 now and am so pleased with and proud of myself for not doing it. I'm glad I didn't have that 'courage' because I now enjoy laughing with my boyfriend, I chat and am cheery at work, I'm doing ok in my A Levels, etc.
You are struggling with your mental health, a battle with your mind, and that is okay. You have a right to be sad, you're allowed to cry and feel like the world deserves better than you. But, you have a duty. You have a duty to yourself, your DH, your DD, family/friends to help yourself. You have to seek help (from anyone and everyone - and medical professionals) to get yourself back. We need you to stay on this planet.
Please, remember this.
You are not a bad mum, bad wife or bad friend. You are not evil or a disgrace to humanity. You are a person, with thoughts, feelings, memories, a beating heart. There are people that want to, can and will help you.
Please, stay strong.
"To the world, you are just one person. But to one person (can be more obviously like your DD, etc) you are the world" - Unknown


