Ask HN: Startup Governance Woes

I'm a co-founder who was removed from the board of a startup I helped build. Still a major shareholder. Recently discovered the CEO and other executives started a new company in the exact same space as ours.

Found evidence they used our company's funds to pay for the new venture's marketing. When I formally requested documents about this, they first claimed nothing existed. After I showed proof of the spending, they created backdated board resolutions claiming it was all a "mistake” absolving them of any wrongdoings and approving that their new venture can be pursued separately.

The new venture is actively competing for the same customers we serve. The CEO and our lead investor are running it while still controlling our company.

For those who've dealt with founder conflicts: is pursuing legal action worth it, or does it just destroy value for everyone? The company is post-revenue with actual customers, so there's something real at stake.

I’ve already spoke with a lawyer and understand all the options available to me as a shareholder from a legal standpoint and it’s all relatively straightforward albeit expensive.

What would you do?