Como dizer "Entrar por uma porta e sair por outra" em inglês

Right at the moment he shows up I am going to leave through another door.

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But then, this doesn´t express another situation, that of an ultimatum "either you choose him or me" for example. If you let invite him, at the moment he enter this place I am out! Or...I will be leaving, etc. To a situation like this, I don´t have a concise expression as yet.
So, that is the closest sentence I got to express that.
But it could be that you had planned something with "him", for example, agreed that he would come at a designed time and his coming would free you to leave.
That wouldn´t be an ultimatum.

If he comes back to the club (or if he is accepted back by the club) the very the moment he gets in, I am out!

I don't want to see him near this club ever again, this club ain't big enough for the two of us! (that could mean, if he comes I am leaving.)