Director wanting to resign or forcing another to resign

I have an equal share of a limited company with 2 others, we are all Directors. The business is doing well however Director A has said he cant work with Director B and that he will resign for the price of his shares. However Director A has not resigned and has now suggested Director B resigns instead. Director C is 'in the middle' but Director A has had meetings with Director C and made C feel like without A the company will go under. D. A has also said if DB doesn't go he will take all leads and set up in competition or suggested the company dissolve.

Can anyone please advise what the credible options are please?

Any help would be much appreciated, Thanks.