Your use of infidelity as an example of losing your faith is very appropriate. I've heard others here express the loss of their faith along the same lines. This might also serve as an example of why so many express such anger and hatred for the church afterwards, the same feelings as one would have towards an unfaithful spouse.
Despite being presented with a vast array of arguements against the church, I have seen nothing that has dented my testimony in the least. Quite the contrary, in studying out the claims I've been able to study things I normaly might not have and received an even clearer picture than before of the amazing breadth of the church and its doctrines.
Knowing whether a feeling was "just a feeling" or "a prompting from the HG", is, by definition, a matter of "knowing". And how do we "know" things, especially things pertaining to "the spirit"? The answer is, through the spirit itself. And how do we know whether it is the spirit motivating our emotions/feelings, or something else?...
I think you can answer this one for yourself. Do you feel that you could repeat the testimony you received on your own? The same way you would feel anger or silly from watching a movie? How, in your opinion, could you re-feel the witnes of the Holy Ghost that you had?
Gaz