I've seen from time to time discussions on struggling with assurance that I haven't stuck my nose into because I didn't really know how to judiciously approach the subject. Recently, however, a blog which I follow posted an excerpt on this subject from Spurgeon's autobiography which I have a hope may be edifying.
Pyromaniacs: Spurgeon's pastoral wisdom in dealing with a woman lacking assurance
Pyromaniacs: Spurgeon's pastoral wisdom in dealing with a woman lacking assurance