I have a sermon...are you ready??? If not...please skip.
Sorry about this...but I loved your original post and your questions and these thoughts are what came to mind...(it got a bit lengthy...and I bet it is stuff you already know...so please don't take it as I am saying things you don't do or don't know):
It is being authentic to have doubts and still try to stay for your family's sake.
It is being authentic to see the good, even if the mystery or magical stuff is not believable.
It is being authentic to love others, and filter your thoughts so you don't harm others and their faith. It is very
authentic and respectful.
It is being authentic to say "I don't believe that" and just leave it at that, without expounding further if it only leads to debate or tension.
It is being authentic to smile, and say "No." (that includes callings and invitations of any kind)
It is being authentic to disagree with boring, stale, pat answers and flowery rhetoric and regurgitated sunday school answers.
It is being authentic to accept yourself and your own views, and still call yourself a mormon if you want to.
When the church leaders state clearly:
"Believe in yourself, and believe in Him. Don’t demean your worth or denigrate your contribution. Above all, don’t abandon your role in the chorus. Why? Because you are unique; you are irreplaceable. The loss of even one voice diminishes every other singer in this great mortal choir of ours, including the loss of those who feel they are on the margins of society or the margins of the Church.
Brothers and sisters, we live in a mortal world with many songs we cannot or do not yet sing. But I plead with each one of us to stay permanently and faithfully in the choir, where we will be able to savor forever that most precious anthem of all—“the song of redeeming love.” Fortunately, the seats for this particular number are limitless. There is room for those who speak different languages, celebrate diverse cultures, and live in a host of locations. There is room for the single, for the married, for large families, and for the childless. There is room for those who once had questions regarding their faith and room for those who still do. There is room for those with differing sexual attractions. In short, there is a place for everyone who loves God and honors His commandments as the inviolable measuring rod for personal behavior, for if love of God is the melody of our shared song, surely our common quest to obey Him is the indispensable harmony in it. With divine imperatives of love and faith, repentance and compassion, honesty and forgiveness, there is room in this choir for all who wish to be there. “Come as you are,” a loving Father says to each of us, but He adds, “Don’t plan to stay as you are.” We smile and remember that God is determined to make of us more than we thought we could be."
- Elder Holland, April 2017 GC
...then it is authentic to take them up on that offer, and be yourself and believe what you believe, and let others deal with it. Church leaders are saying there is room for you in the church, as you are. You do not have to try to wear a mask or be different before you can do church the way you want to do church.
It is between you and the Lord...and if you don't believe in God...it is you and the universe and whatever you believe. What others think does not ultimately matter.
The Church does NOT want you to be inauthentic. That is not in harmony with its teachings.
"I've told him I plan to attend church with the family but not hold a calling or go visiting teaching."
That is great you are supportive and loving in that way. Attending for the family and allowing the children to grow up to learn things and make up their own minds is authentic, not anti. It will take its course.
"I would love to get your views on how to balance holding to my decision of being authentic while also not having everyone at church find out I am not believing."
My opinion is to find a peaceful place for yourself and your faith. If people directly ask you, answer it, even if that means they find out you don't believe many things. If they don't ask...keep thoughts to yourself.
Look for a middle path, that allows you to be your agnostic self, while also seeing the good the church teaches and does.
Are you agnostic about loving others or serving others?
Are you agnostic about finding peace and happiness in life?
Are you agnostic about living in the moment and letting go of fears of the past or the future?
These are questions you can wrestle with on your own. Church is a buffet, not an all or nothing proposition. Life is more complex than that, even if others disagree and simplify it to make themselves feel better (that is about them). Take the sacrament, and ponder the things that matter to you and your heart and your spirit. Turn the sacrament into something that is meaningful to your soul...and use that power within.
Pay attention to the things that really bother you and that you can't let go of. Find out why. Find out what you think about it, and what you believe.
Allow others to believe the way they do, and you can be on your own path to find out what you believe and have faith it. (It sounds like you are doing this already).
You may find you and others are all walking along the path together, despite different thoughts and feelings and stories in our heads we tell about the path. Those are just stories to frame things to talk about.
You can learn to become comfortable with paradox and different metaphors that try to teach universal truths.
Cling to the good you can find, where ever you find it. Let go of the rest.
You may find you fit in just nicely with other good mormon people who believe God spoke to Joseph Smith in order to teach people truth. Regardless of what the story details are, focus on the principles we should all seek for in this life.
And be authentic to that, including how you be loving to others who believe in things you do not believe in. The rest will take care of itself.
In the world we now live in...it is more and more common for people to not really believe the magical mormon stuff as literally true. You will not be the only one in the ward with a spouse who believes it one way, but unable to believe it the same way yourself. You are likely to bump into others with the similar family dynamic. You may even be able to provide and example and provide strength to others on how the home can stay harmonious despite the dynamic.
I imagine if you go to church on your terms and be yourself, others will respect you for it...most especially your children as they grow. And that is all that really matters.
Be authentic, whether you believe or disbelieve. Being authentic is not being anti and angry and tearing down others (which you know). So separate those out and be yourself and do church how it makes you happy. Let the chips fall where they may. Others will respect you when you are authentic and you go about doing good in your life, and love your family and lift those around you. Regardless of the details of whether you believe we'll be building planets in the next life or doing missionary work or doing anything. Most people kinda agree all that mormony stuff is kinda silly anyway. But some hold it sacred...and we respect that if they do.
Today is the day to do good to those around you. And that will win the day. Always seek to be authentic in all you do. And celebrate your uniqueness, and all your accomplishments...and let that light shine to others so others know it is safe to be authentic too. Others may need that light from you.