My father gives money to all kinds of people without telling my mother. He’s a completely upstanding, generous Christian man. They are from an older generation.
That's commendable. I'm certain that as a Christian gentleman he also takes care to obey the biblical injunction to "be above reproach." That includes any behavior which would appear to be suspicious, such as hiding a 13-year relationship with a woman which involved money and middle-of-the-night calls/texts. "Upstanding" Christian men do not do such things.
The evangelist Billy Graham took great care not to be seen as having any kind of relationship with any woman other than his wife. He would certainly not travel alone with a woman, or even be seen privately with another woman. There was never a hint of scandal associated with him. Similarly, my godly childhood pastor would not counsel a woman alone in his office - the door was always cracked open and his secretary was right next door.
That is how godly Christian men behave, as I am sure your father would affirm.
I’m 54 and my Wife would shoot me.
Sorry but, that’s not right IMO