I’m a woman CEO and in couple with my Co-Founder (CTO) and he cheated on me. He’s now trying a takeover of the Startup.

id first switch lawyers. A statement like "this company is my life" is worth a lot and as cliche as it sounds dont go out without a fight. Even if it costs you all the savings, hire the best damn fighter laywer. It might get to be you or him in the company but so what there are plenty of CTO's in the Bay area but not plenty of places you can call your life.

Don't know your peculiar situation with board etc, but try to win the board members one by one on your side. If I were you Id let go of the cheating part and play the "non-teamplayer" card when approaching board members. Your approach to the board or employees or whoever has the voting power:

"he cheated, broke up and I let all those go for the sake of the company, yet he wants to get rid of me, do you really want still be in business with someone so illoyal ?"

if still goes to shit, you'll at least know you gave it a try., good luck.

Are you sure you're not the ex, anonymously trolling for advice on how to reverse-engineer a legal retort?

Hey a better lawyer and get rid of the ex. No company is your life. They are not your family. This is business. You don’t have to accept a bad deal. If anything, since it’s sexual, there’s ground for a case.