If he wanted to start with a less-experienced technical person, and jettison them early on -- he could have hired an employee and paid them.
Instead he co-founded with you, as a partner. He was happy to take your money -- you have skin in the game. He doesn't get to shoo you out the door now like a temp.
He also doesn't get to do it via the CTO. He owes you a frank conversation. Also you need a lawyer.
tl;dr: From hearing your side of the story, although the CTO is handling this like a tool, the CEO is the biggest schmuck.
Definitely lawyer up, that would be a first thing. Then, if you want to regain control about he company, consider CEO your enemy, not the CTO. Invent a reason and fire the CTO, if you can do it. Then, step up as CTO yourself, or at least hire a person you trust. Then, hire COO, CFO, CMO. Make sure those are people that are loyal to you and where each one will take over one of the CEO responsibilities. At the latest stage, let those people document every mistake of CEO, and you try to push him out together with C team and investors.
That's exactly what he is doing to you. He convinced you to voluntarily step out from CTO position and hired his tool. Now, your chances to fight back are much worse from this position, but the war is not yet over.
So, lawyer up, read Machiavelli, know your enemy and fight fire with fire. Remember, the CEO that did this to you is not your friend anymore, and deserves whatever you do to him.
45% share of 100M$ worth company is still much more than 10% share of 200M$ worth company or 1M$ compensation. You are not fighting to optimize for the company success, you are fighting to optimize your own wealth. If the company gets destroyed, and you still manage to get more then what would be your compensation package, you are still better off then retreating. Why caring about the company that doesn't benefit you, you would certainly not enjoy the success of the company that squeezed you out.
So yes, lawyer up and fight if it's worth to you to fight for the control. Don't be emotional about he company and business. It's your weakness, and they are already playing on that.
I think this is being overlooked. You invested all your personal wealth into this company and in return you got unvested shares?
There's this underlying meme in our community that "elbow grease" investment -- working for low pay, no benefits, rejecting other career opportunities -- is somehow worth less than an investor's cash. IMSHO, it's just the opposite -- cash typically doesn't draw down one's pool of emotional well-being and spirit the way hard work does. Work investment should be rewarded with a premium, not treated as somehow less than just money.
OP's situation sounds more like a bootstrapped small business where he invested his life savings and blood/sweat/tears. I'm not sure that vesting shares is ideal there -- perhaps a well defined shotgun clause or similar is more reasonable to handle unruly founders.
Either way, if possible, figure out a compromise which feels fair for everybody involved. This doesn't need to be completely one-sided.
Being asked to "leave in 3-6 months" is the new CTO's opening gambit in the negotiation you're about to start.
Your _worst_ negotiating option will be to say "OK, bye".
Work out what you want.
Work out your best idea of what the CTO/company wants (depending on what you want, the first step here is most likely to be asking them outright - if what you want most is to get rid of this CTO, this step will need to be approached much more subtly and delicately, and probably with someone much more experience helping you out).
Work out some "next best alternatives" to your optimal outcome, and what you'd accept as compensation for agreeing to those non-optimal alternatives.
Mostly though - work out what _you_ want - and why, and once you've done that, look at it with the most objective view you can and determine if it's actually plausible and realistic. (To be honest, a guy who wasn't even writing tests a few months ago _isn't_ going to be the technical lead or chief architect of an enterprise software startup - at least not a startup with a high chance of succeeding or getting serious funding. Be realistic here.)
If it's just the vesting(/money) - you'll negotiate one way. It's it's actually an ego/ownership/founderdhip issue for you, then acknowledge that (at least to yourself) and work out how to negotiate your desired outcome while keeping that perspective firmly in mind (and seriously, think about whether you need to rethink that - if it's mostly an ego thing).
This is negotiable. But you shouldn't necessarily be the one to negotiate it, so you should probably start talking to your own lawyer (not the company's).
You can try to negotiate a settlement (still consult a personal lawyer) of retaining some of your money put in (maybe after they receive investment) as well as an additional accelerated vesting of a small part of your remaining unvested shares. You still have some rights to make a big stink about all of this, but I wouldn't advise trying to stay on. You may end up with nothing and have burnt some bridges with the CEO and future investors.
I would work on retaining control of the company and your shares, possibly isolating the CTO in terms of power, if not outright dismissal.
The CTO is way out of line speaking to a board member, and majority shareholder like that. I assume you are a director and hold ~50% of the company in addition to a few of the officer positions in the company. Utilize corporate law to eliminate risk to your portfolio.
The tech shit is completely irrelevant, you should be discussing with the other shareholders how out of line the CTO is and your contingency plan for dealing with officers who are not respectful of the owners of the company.
Also check whether the company owes you any debt, if the other founder can't come up with the money you could also use debt to take control. Again, talk to a lawyer, and keep in mind that it doesn't matter if the company tanks if you're not going to be part of any success it has. Scorched earth the mother fucker if no one wants to play ball. (Shareholder and board meetings can be a great way to get internal feuds into the corporate minute book)
Do you think anyone at Facebook cares that Mark Zuckerberg is not their top coder? (And even if he was do you think that the best value he could provide to the company would be from writing code?)
> The rest of my advice assumes the CEO (your co-founder) has quite a bit of confidence in the CTO.
This is the case, it is in my interest however to remain in the company because my equity is vested, the sooner I leave the less I will get in return, apart from my time, and opportunity cost I invested all my personal wealth.