I'm not sure why this is being judged bad advice, because this is certainly the path to the least painful solution. If lawyers get involved you're going to burn

I'm not sure why this is being judged bad advice, because this is certainly the path to the least painful solution. If lawyers get involved you're going to burn through any profit you might have had and for what -- to win a moral victory? You need to speak to this person -- face to face ideally, on the phone if not -- and ask what their ideal outcome is. You need to explain, in a reasonable way, what your ideal outcome is. Then you need to talk, and to come to agreement. You might find that he'll settle for 20% of the company and some cash. You might not like it, but that might be a great solution -- 80% of something is better than 100% of nothing. The 80/20 figure is just an example. When things turn nasty you end up with a zero sum game at best, and quite often you end up lose-lose. You CAN make it win-win again, you just need to detach your emotions and do what's best for you both.