Going back to the original question of the thread, it’s starting to sound more like a grieving process than an answerable question. How do you open source the code? You flip it from private to public. That’s pretty much it. Well, okay, maybe an over-simplification.

If the business is small and profitable but it’s not growing how you’d like then I’d probably be more interested in selling it if it was me. I am not sure you will be able to sell it if the code is all open source.