Possibility of acceptance when the editor clearly states that another revision will likely lead to a rejection
I understood from the question that you are asking whether to do the second major revision or not since the chance of acceptance is low. 

I think it's better to go through with the second major revision and see what will happen. If you think the other referee's notes (aside from the one you think is biased) are valid, and doing those revisions will enrich your paper, then do it. 

Your relationship with the editor do not end with publishing this paper or refusing to publish it. You may probably deal with the editor later in your professional life, and you might submit another paper to the same journal despite how this paper will end. So you wanna maintain a relationship with the journal editor. Stopping the communication about this paper without providing a valid reason is not good idea. 

Good Luck!