The first mistake was to agree to the leader's request to enter B.
The second mistake is, since you promised the big leader to help in B, why didn't you mention the conditions at that time?
So all he has to do is run the company well and make money. As for you being wronged, it's really a trivial matter. Now that this has happened, we can only find a way to solve it. Judging from your description, it is the type with stronger working ability than emotional intelligence. Since the big leader is a shareholder, he has a voice in this branch. As long as he talks, you can still keep your position. Therefore, the key is great leadership, and you can't be well protected. If I were you, I would take refuge in the big leader. Where do you want to continue working? Obviously, B is not one of our own. People think that you are on A's side, and A can only ignore you in order to reduce the contradiction with B, otherwise B will have a lot of gossip. And the big leader always asks B to answer questions and help you. Of course, he also sticks to his principles and is afraid of offending B, so you are in an awkward position and pretend not to see it. But in my opinion, although the position is embarrassing, it will not make me lose my job. Obviously, it is difficult for B to quit you in front of the big leader, because you were dragged over by the big leader after all. So the key figure in your question is the big leader.