There are cisgender men who desire breast development and take estrogenic substances to achieve it. There are cisgender men who take estrogenic substances to achieve certain mental benefits. A common concern of these men is the loss of male sexual function and fertility. Some will go off estrogen on a schedule to counter these inevitable effects.
We must remember that both sex and gender identity fall on a spectrum. Predicting how changing your T/E hormone balance will affect you will quite often turn out to be wrong. You'll just have to try it, preferably under the supervision of a qualified doctor.
Keep in mind that some men's feminine proclivities are induced by their body's natural testosterone production. When taking estrogen, and thus driving down their testosterone levels, the desire to cross-dress, for example, disappears. On the surface, it appears that taking estrogen resolves the gender identity conflict. But as soon as they stop taking estrogen, their natural testosterone levels are restored and the cross-dressing urge returns.
When people fall closer to the center of the 'sex spectrum', a gender tug of war often ensues, producing the diversity of gender identities that we witness today (bi-gender, gender-fluid, non-binary, etc.). It is my personal observation that relatively few in-the-middle gender males resort to medical intervention to address perceived conflicts or reservations they have about their gender identities. Doing so compromises their sexual identities as males which is not something they want to completely abandon. This is unlike those born male who have no desire to be male and eagerly seek medical treatment to correct what they see as a ghastly mistake of nature.
The evidence points to the fact that the number of people who seek medical transition to the opposite sex are relatively few compared to the 1.7 million who identify as transgender. I don't find that surprising given nature's strong bias toward mind-body congruency. Be that as it may, the in-between sexes have been with us from ancient times. Cultural and religious gender standards have for centuries forced in-between people to conform to the binary model. Now, in today's less oppressive cultural environment, we find ourselves having a choice as to how to express our unique gender identities, and it's causing many to make choices they might never otherwise make, learning, instead, to cope with their gender issues.
The unfortunate truth is that society is not fully on-board with the gender spectrum. Coming out to a spouse after marriage with children is often fraught with heartbreak and dislocated lives. In this more progressive cultural state that we find ourselves, more and more gender dysphoric people are coming out to their families with devastating consequences. I always caution those struggling with the decision to first accept the possibility that you will lose the people you love, and a lot more. Once you come out of the closet to a loved one, there's no way to go back.
If you treasure your love relationship, but decide the risk of revealing your secret is worth it, the chances of preserving that relationship are much better if you make the transition together with both of you open to compromise.
Don't rush into this. It could be the most important decision you'll ever make. Good luck.