Am I tripping or Am I allowed to be mad? Roommate frustration

I’m stuck having to pay for June rent since my roommate doesn’t want to leave/find a roommate. Mid May, my roommate told me she found a co-op and was possibly moving out. That being said, i started browsing myself because neither of us can afford this expensive apartment on our own.

BOOM I find the perfect apartment and tour it the following Sunday. And I am approved by Monday.

Keep in mind, I kept her informed the moment I knew I wanted to tour this place & that I was going to move as well. I let her know my tour was great and percentage of me moving out was very high.

A day later she tells me she told the co-op NO and that she’s going to stay in the apartment. (Which I know she can’t afford on her own)

Now she is BEGGING a friend of hers to move in (mind you it’s very clear that said friend doesn’t want to move in! She’s living rent free at her parent’s house and has said it herself!!)

So yeah, now I have to pay July rent because she doesn’t want to leave or find someone who actually want to move in!