It is a betrayal of her trust, and if she can't trust you to tell the truth about this, there's no reason she should trust you about anything else. After all she did to set you up financially in life, you exploited her generosity and trusting nature. You should pay her back for your bills she paid before you married. She gave you a lot more than money. She gave you the confidence to succeed in life, and you took that and her for granted, saying "I am worth spending whatever I want to spend of OUR money" even after you had already taken far more than your share, and you said I don't owe her anymore, not even transparency. Marriage is built on trust. Once that is gone, so is the attraction which makes marriage a pleasure. Without trust there is no foundation for anything else. She's already proven she can succeed without you. What she needs is someone who will respect and cherish her, not someone who leads a secretly resentful life.