Would you be mad if your friend tried to befriend someone who treated you like shit?

Extra info - this girl told me she hopes I die and that I'm a slut and that i better watch my back cos if she sees me I'm 'done' because her boyfriend came on to ME... anyway few months later my friend says the girl said there's no hard feelings cos she's broke up with the dude and said she knows it's his fault (uh hell no, you can't just take back the nasty shit you said to me) and started going on how decent that is of her and she doesn't blame her for acting the way she did and went on to talk crap about their super fun night together (were clubbing). Would you see this as betrayal?? Like that's my best friend out there talking up and hanging out with a girl who was awful to me