What should i do about a best friend who betrayed myself and my other best friend?help?

ok it was the last day of school we have this little trio including me, w, and g(lets just call them that) ok so w was making a big deal about ho we need to spend the last day together and stay friends and every thing but hen the last day came she kept ditching us for her other friends so we were like ok whatever shes ditched before then we all had to go back to our cles and we had the cl together. then she ditched us to go talk to the guy ive had a crush on since before the begining of school(FLIRTING!) if that were not enough here comes along the guy that g has had a crush on since FOREVER so she starts flirting with him too and she knows that we both had huge crushes on them. so then the final bell ring and we wait outside for her so we can all say bye to each other but she walks right on by but shes not alone th guy i like is with her. She flirts our guys, ditches us, makes a huge deal about not seeing each other yet doesnt even wave so tell me what should i do?