There is nothing to live for but pain and misery.

Well, actually, no. If you keep going in life (and I strongly encourage you to do so), the chances of something good happening are astronomically higher than if you ended everything right away, talking from a strictly statistical standpoint.
Of course, there's also the bias of our minds, since the human brain is far better at noticing/remembering bad situations than it is at enjoying/recalling the good ones.
So, please, don't do anything stupid.. could you tell us more about what's going on? Maybe we can help? I'm sure people here can help you!

(although, actually, I lied, I think you're right in saying what you said, but I highly doubt it applies to you, I just think your mind is playing tricks on you)

 

Emotions aren't real, you know. Pain and misery are just our brain's cognitive labels for physiological and neurological sensations. People who see the world through an optimistic, happy lens see it that way because they lack the mental and biological processes and negative stimuli that cause excessive negative emotions. You can be happy if you reduce the stressors and negative thought processes in your life. And of course medication can improve your mental state tremendously. Pain and suffering are not inevitable.
Sorry, I doubt this is very helpful but personally I always find it reassuring to look at things from a detached approach.