Your decision to implement disiplinary against your employee I would say was correct as long as you've covered your ass using the correct protocol....i.e previous verbal warning all recored on paper etc.

As one of 3 in a medium sized business the key to any partnership/board in my experience is to always have a united front to the people who work for you.

No business can survive if there is dissent in the management whether that's 2 or more.

As for the partners they need to be able to talk about any subject..however hard that maybe(family ties/friendships always make this more difficult)...and if no solution is forth coming the only option is for one or more to leave the partnership

Take some very good advice from both your accountant and solicitor and play your cards close to your chest initally and try to hide any emotional attachment you have to the business....

Lastly and again only my opinion dont work somewhere or with people who make you unhappy it will only lead to you becoming de-motivated and stressed....life is too short....

Hope this helps

Regards

Ian