Depression Support Group
Depression is a real and debilitating condition that is often misunderstood by family and friends. Its meaning can range from a prolonged period of sadness to an actual mental illness with specific symptoms. Find and share experiences with others who are going through the same struggles.
Also, remember that while you can do everything in your power to make people happy, and they still might not be. There are some things that are simply beyond our control, and we have to focus on the things we actually have control over. As long as you are being kind and supportive of them, you are in no way a screw-up with the ones you love.
It sounds to me that you love your daughter a lot. You wouldn't jump on a plane and take off without telling her, because it would hurt her. Think about how much more it would hurt her if you were gone forever, not just a few days. The hard times will pass, they always do. I know it doesn't seem like it now, but things always get better. If you ever need someone to just vent to, send me a message. Just don't give up, the world needs more caring people like you. :)
Definitely focus on yourself, you sound like you already care enough about other people so you don't need to worry about that. Sometimes it's hard to work out what will make you happy, but you can work it out.
I don't know your situation, but I want to suggest that maybe you look too much outside of yourself, at other people, to be the source of your happiness? This may not be the case, but give it a thought anyway.
You sound like a lovely person, you seem to be smart and caring. And I don't think suicide would be a blessing, I think it would hurt others around you even more, which you don't sound like you enjoy doing. And you sound like you have the strength to turn things around.