Backstabbing friend

I just became back friends with my former bff last August and we just stopped staying friends lately since last week I told her that I’ve changed and I didn’t want to be friends with her anymore. She agreed and we said our goodbyes and hung up. Yesterday she sent me a random text calling me a slut since I had a bikini pic up of myself on MySpace (she has always complimented and has even told me that she has wanted my body). I told her to please respect my life and if she doesn’t then fine, just leave me in peace. She just kept on texting me calling me trash, whre, btch, skank… you name it. Just because I have a great boyfriend that I’ve been with for 10 months now when she has nobody and all the guys she’s been with have done her wrong. She was just saying all the stupid crap about she can’t wait until he breaks my heart. I just can’t believe I let her back into my life and I should of known this was going to happen since she did the same BEFORE when we weren’t talking last year!!! I feel SUPER betrayed since I let her back into my life and now she’s betrayed me and is being immature about me spending a lot of time with my boyfriend. Why can’t she be happy for me? I just feel so betrayed and stupid for giving her another chance. I feel like getting her back but I’d just be stooping down to her level. Ugh! Please help me!