I don't know what to do?.?

My good friend Nicole is dating my ex, Zeke. She spends the night with me and stuff. She considers me a best friend and writes " I LOVE YOUU " on my facebook wall and crap lke that. She's also dating this guy named chance. We went to the skate track, she was alll over him. When we get back from the skate track, shes on the phone with zeke telling him how much she loves him. She's also dating my OTHER ex, Riley, (who I still care about, She didn't know I dated him) She's also flirting heavy to another dude named Austin.. Alll in the same day.. Sad thing is, she reallly doesnt give a damn about any of them and is using them for her entertainment. I still care about zeke and riley. What should I do?