Como dizer "separar as coisas (não interpretar de forma errada)" em inglês

I'm not going to leave him out of my championship just because he let me down in the past; the past event is unrelated to the current decision.

In other words, emotions and business don't mix to cloud judgment or affect future decisions, decision-making might be neutral, or professional.

I am sure others will get our sentences and make a more concise one.

Your example is okay, but I think it's not that common in spoken English.

I've just looked into it some more, and I found another common way to say "separar as coisas"

You can also say...

I can/know how to separate the two.

I've also just checked it with an American friend, and he said my second sentence in the text above sounds natural.

"One thing has nothing to do with the other" this one also works fine.

Fine, thanks for sharing the sentences with us, I am glad for learning new things as well.
One more sentence from the site Sounderatheart.com

Despite those feelings, Lodeiro is clear that he is still committed to the Sounders.
“One thing has nothing to with the other, ” Lodeiro stated with assertiveness. “I can have a special affection for Boca and Nacional, but I am devoted to the Sounders.

Anytime my friend!

I appreciate your help and effort in trying to help me out with it. Keep up the good work!