Divorced founder here. I had this experience.
It really works to establish this before you get married.
Since the journey you are on, as you say, it really works when your life partner buys into your vision.
You are going to be making choices about how to work, when to work, and with regard to the current burn rate of your life, and with regard to the value of future pay offs, that are vitally important for people in a relationship to agree on. If your partner doesn't share your passion for this, or believe in you, how are they going to come on that journey with you? Will they be there for you and support you when you and your business need that?
Will they give you the extra runway by getting a job, or will they insist you chuck it in and get a job?
I mean, having a business is a lot of ways like having a baby, you are always working on it, and everything changes around doing it. And it really works for your partner and you to carry that weight together.
No one knows what's going to happen, it could all work out. Maybe it's simply differences in expectations that can be reconciled through communication. Or maybe it's something more fundamental. At this stage tho, you don't know.
My choice was to cut my losses quickly when it seemed like it wasn't working. I would caution against that, since I feel that the marriage is an asset, because of your commitment to each other. When you got married, didn't you vow to be there for each other, through sickness and health, and failure and success? So my recommendation after trying the opposite ( and it not working ) is just stick it out. Try to make it work, because that relationship could be so important to you if it maintains.
In my case, we divorced. Not, mind you, just because of a business. There's always a mix of things, and both people are responsible. I think the main thing was simply not really emphatically communicating about what our expectations were, and also not really being so committed to sticking it out, we both chose to cut our losses. Well, at least we had the same efficient mind! Still I believe through lack of communication and commitment we didn't quite work out exactly what it could have been. So persistence, could really be key.
Later I found someone who really did buy into my vision, and support me while working on the project. Objectively this person is far more compatible with doing this startup, tho the truth is, you never know how things could have been different, had you done them differently.
As other posters suggested -- maybe get some husband time to yourself, away from the wife and kid, cafe working, or cave working, or shed working, some time and place to be around other people who do share your vision. I think that idea of community really helps. Why? Because in a way you are asking your wife to be your community if you don't get out there and rely on others as a community. And being around the energy of others can really refresh you and give you that mental reset so when you come home, it's like a delineated time, and you're all ready to go husband and daddy mode again.
It is a scary time. Maybe rethink feeling ashamed, tho. You're trying to juggle doing a lot of things. You're not doing anything wrong -- you're just trying to make it work. That's noble, not shameful.