She was a guest on Watch What Happens Live.
It's very sad that their friendship ended but it's true people grow apart. And when she played Marry/Shag/Kill she killed Bieber. So I'm guessing Selena's obsession with Bieber had something to do with it. This is life. They'll both be fine.
Why are people getting mad? People grow up and people change, and your friends change. It's not surprising. It's not like she said anything bad about her.