One of my best friends is angry and upset at my other friends&I

One of my best friends is angry and upset at my other friends&I because are all in relationships and she isn't. She told me that I make her sad because we were single together but now I have a boyfriend. She doesn't talk to me anymore, and she talks about us all saying she can only stomach one out of the four relationships and that she will never be happy for us. She also said that she hopes one of us breaks up so that she doesn't have to be single alone. I understand that she feels lonely because I've used to be that friend, but I find it kind of selfish of her to say all of this about us. I mean, she's the one who helped my boyfriend and I hook up. I just really don't know what to do. The only way she'll be happy is if one of us breaks up with our boyfriends, but that won't happen. I'm just so confused. And another thing is that she likes someone and they like her back, but she doesn't have the guts to ask him out. I don't want anything bad to happen. I just need help.