Did I do the right thing?

There's this exchange student from Germany who goes to school with my boyfriend and I. For as long as I can remember, she has been trying to steal him. I'm not really too sure why, because she has to go back to Germany, but she is. She has been constantly flirting with him, sending him hearts, telling him she misses him, and trying to convince him to go to the movies with her or hang out and she even asked him to go stay at her friend's house with her because no one would be home. My boyfriend and I got into a little fight because every time I saw him at school, he'd be with her and she'd always be cuddled against him or hugging him. The one time I actually ran into them, she stood off to the side, didn't say a word and kept giving me dirty looks until she eventually gave him a big hug and walked away. He went on a field trip in a cl he had with her, and she took a bunch of pictures of her cuddled up against him. I was really upset about everything and he spent the last week trying to make things right with me, and she was texting him the whole time begging him to hang out with her so he said he would and I told him that the only way I would let him, after everything is if he brought me with him. He ended up spending that lunch looking for someone, but every time he went outside to go wait, the girl would ditch her friend and go stand right beside him and every time he moved, she would move and go stand right beside him again. Her profile picture on facebook had been of him and her and she had posted Teardrops On My Guitar by Taylor Swift. Yesterday, I was really upset because the only times I had seen him that lunch were when he was with her and he explained everything to me and he texted her and told her to lay off because he had a girlfriend and him and me ended up walking past her while she was running track and she sped up and kept running. I ended up creeping her facebook later and she had posted You Belong With Me (again by Taylor Swift) on her wall, with a broken heart and a crying face and had changed her profile picture. I feel really bad for getting him to tell her to lay off, but I really didn't know what else I could do and I didn't want to have to wait the next month for her to leave, with her STILL trying to get my boyfriend. Did I do the right thing or should I have just let it go?