All of the advice about your husband regretting his decision, having a mid-life crisis, being immoral, etc, is unhelpful. The fact is that we all do what we think is best, and it's really not the job of other people to judge. The only things that are relevant to you, IMHO, are that he's decided to end the relationship. Your focus should be entirely on moving forward with your own life, and respecting what you had together for so many years. Don't ruminate over what he is or isn't doing, or what motivated it, or whether he'll regret it or not - they're all
his issues, not yours. I liked Sunder's advice.
So, what stunned all was that everyone knew him thought of him as the most morally righteous person and would be the last person to do what he did - he is a professed Christian and a deacon at our church! ... I am still pondering the question why a loving and caring Christian person could (because of his lust and infatuation for another woman - and she has not stopped pursuing him) turn out to be the opposite of what he stood for most of his life. I never thought that one day he would behave like this - as if he was possessed by the devil.
Forget all that. His relationship with God is between him and God; it's nobody else's business to judge.
And whilst I'm very pro-marriage, I agree with coastymike that the "behind every good man is a woman" statement is patronising. I get that it's catchy and has some truth in it, but in this situation, it's inappropriate and encourages judging. I'm sure both parties contributed to the marriage for 30 years, or it wouldn't have lasted this long, and both enriched each others' lives. But now it's over, and seeking to blame and judge just diminishes and disrespects what babushka and her husband had.
Good luck, babushka, in finalising the financial agreement and creating a wonderful new life for yourself.