You write that your boyfriend is hanging out with this person as if nothing is wrong. That’s because nothing is wrong to him. Unless your boyfriend is himself toxic, it’s unlikely he’s hanging out with the toxic friend to spite you. So don’t take it personally.

He is known as an egotistical bully, and I believe he uses his friendship with my boyfriend to elevate his own image and legitimize his toxic actions.

I would never give my boyfriend the ultimatum to choose me over his friend, but I have to admit, I feel some resentment every time he spends time with him, which is affecting our relationship. My boyfriend is aware of my feelings regarding our mutual friend,