I think your cofounder might be annoyed that you took two days off, came back and changed the work they'd been diligently working on while you were gone... and

I think your cofounder might be annoyed that you took two days off, came back and changed the work they'd been diligently working on while you were gone... and then wrote a blog post about it? Seriously. What have you actually learned here... it should be more than "treat others the way you wish to be treated" in my opinion.