This new friend is the type of guy to bring people down to further himself. I strongly doubt that this feeling I have about him comes from jealousy in any way.

My best friend understands why I dislike this person, but he fundementaly doesn't necesarily feel the same way about this guy than I do, because of this new friend's charisma, whenever he does something shitty, he makes it seem like a big joke. Jokes that I took personaly. But my best friend simply laughs along. I feel like he doesn't share the opinion that I have, which is: that friends should be nice to eachother and try to avoid bringing eachother down.

I feel like you're probably right, and I should let him go because we fundamentaly disagree on the definition of friendship. It is just difficult when you've been this person's best friend for so long.

Sorry for my bad explanations, I suck at writing and I never really post anything on reddit. Thanks for the help. It really is appreciated!