Is it normal to react this way

About two months ago my best friend got into an argument with one of her friends who totally disrespected her and even threatened me with a bat since I was trying to defend my best friend . It's two months later and my best friend sends me a text saying the girl has been apologizing for everything she's said and wants to go get coffee and my best friend claims she only wants to be okay and not friends again with this girl . Now my best friend post on social media both of them doing more then coffee like getting nails done and everything . Now I no longer want to be best friend because I defended her against this girl who threatened me with a bat and she goes and does this . Is it normal for me to be upset and want to end our friend ship?