Your wife's lucky to have you in her corner, with you being someone who wants the best for her, someone who can relate to what stress can do to a person (especially someone running their own business), someone who who has a constructive vision of the way forward. Sounds like her vision is not the same as yours. Can she only imagine coping on her own without strategic mental health support? Does she refuse to imagine anything else? What was it that opened your mind to seeking counseling when everything felt like it was getting the better of you? Was it how stress had mutated into anger perhaps? No need to answer :)
Would you say, based on your own experience, someone can guide you with how to run a business but such guidance will only work under the right circumstances. With ideal circumstances perhaps being good mental health, strategies/tools for coping with triggers, an open mind (inviting outside the square ideas at times), knowing your tolerance levels etc, I imagine what you gained in counseling included some of these things and more. With you being in analytics and with you having faced a lot of stress in the past with your own business, I can imagine you could relate to how analytics and high emotion don't go so well together at times. You could offer your wife the facts but under the circumstances of high emotion perhaps it's almost impossible for her to relate to the facts without a mind free of emotion. Not sure. What do you think?
Being a sensitive gal, I can easily relate to the ability to feel just about everything quite easily. Being sensitive, I can easily sense/feel a stressful situation, sense/feel my own frustration, sense/feel that vision in my mind of there being no clear way out of an overwhelming situation. While some folk may say 'Don't be so sensitive', I think to become more sensitive is key. To become sensitive enough to feel the very beginnings of stress is something that allows you to cut off the build up to major stress. As you would know, there are skills that come with this.
What do you think your wife would say if you asked 'Do you believe you'd be able to feel when it's time to seriously look at managing the stress you're under? How much stress would you allow yourself to feel before seeking ways to manage?' If your wife has a good imagination, it might be easier for her to imagine what breaking point looks like, rather than telling her she's reaching it. Often, the mind will open through imagination.