The analyses of a text #1

The narrator recalls his adolescence.
Doctor Strong's young, attractive wife speaks her sincereness about the Doctor.
People have suspected Mrs. Strong has a love affair with her cousin Maldon, who has reluctantly been to India for job.
And her mother has continuously asked Mr. Strong to support her family members financially.
Mr. Wickfield is the local lawyer and Doctor Strong's friend.
Here "he" refers to "Maldon."

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'When he was waiting to be the object of your munificence, so freely bestowed for my sake, and when I was unhappy in the mercenary shape I was made to wear, I thought it would have become him better to have worked his own way on. I thought that if I had been he, I would have tried to do it, at the cost of almost any hardship. But I thought no worse of him, until the night of his departure for India. That night I knew he had a false and thankless heart. I saw a double meaning, then, in Mr. Wickfield's scrutiny of me. I perceived, for the first time, the dark suspicion that shadowed my life.'
'Suspicion, Annie!' said the Doctor. 'No, no, no!'
'In your mind there was none, I know, my husband!' she returned. 'And when I came to you, that night, to lay down all my load of shame and grief, and knew that I had to tell that, underneath your roof, one of my own kindred, to whom you had been a benefactor, for the love of me, had spoken to me words that should have found no utterance, even if I had been the weak and mercenary wretch he thought me - my mind revolted from the taint the very tale conveyed. It died upon my lips, and from that hour till now has never passed them.'
[David Copperfield by Charles Dickens]
1. I'd like to know what "words that should have found no utterance" means.
2. I'd like to know what "it" refers to.
3. And I'd like to know what is the subject of "has never passed."
Thank you in advance for your help.