I grew up in a small business family, where the business was the sole source of income for the household.

I'm also an introvert, who needs a designated sanctuary (and time) to recharge the proverbial batteries.

The situation you described would be intollerable for me. Everything in life needs limits and boundaries.

Sometimes people work from home, but honestly, you're homing from work at this point. How and where do you get away from it all? The way you describe how the side business has taken over the house, and your spare time, sounds excessive.

It is really great that your wife has this side business and it's doing so well, but again, everything in life needs limits and boundaries, and it sounds like the business has outgrown and overgrown that original plan. I'm guessing since it started more like a side gig, there is no actual original plan. Businesses, especially successful ones, need plans. What is her plan? Does she have one? At what point does she hire other people instead of depending on you? At what point does the business move into a commercial space, rather than continue to take over your personal space? These are fair questions.

And it's nice to be a supportive spouse, but you also need to live your own life. If you want to help her, great. If you don't want to help her, no one should fault you for wanting to live your own life in a reasonable way.

The red flag that concerns me is that she used the threat of separation, presumably/potentially as a manipulation tactic to bring you back in line. That's a bit heavy handed, and might suggest that she's very focused on her wants, while not seeming to be able to take into account that you (and your child) have needs as well. That there are three of you who utilize that house as your homebase, and her use of it makes it difficult for you (and possibly your child) to use the home as a home.

I don't know the answer to your dilemna, but you probably need to express your concerns in a proactive way that might lay out some boundaries. It's absolutely fair to sit down with her, tell her how impressed you are with the business she's made, but that you're overwhelmed and need downtime and a home life too. It's okay to expect her to help make a plan that everyone in the house can be comfortable with.

Good luck