If you've decided you can't then there's no hope.

Might be better to decide you can and will - and do as Pastthemirror has suggested - distract yourself with things on the mundane world. Write (about anything except spiritual matters), play music, watch comedy TV, take up a craft, dance, read between the time you go to bed and sleep so you don't fall back into your negativity. And hide those spiritual books until things brighten up. Look for something good about every day on the mundane.

There's nothing worse than deciding you can't do something that you really need to do.

If you really can't then you need professional help.