boyfriend plus ex girlfriend???

my boyfriend is in college and he moved into a apartment with three other guys all from the college. (i live on my own) and his roommates are friends with his ex girlfriend who completely hates me because she thinks i stole him? i don't know really understand. anyways, she and a friend were staying at their apartment before they moved into their own, and every time i came over, she made me feel really shitty and self conscious. (she also overheard me and my boyfriend talking about my eating disorder, and she uses that against me.) all the roommates plus my boyfriend stand up for me though. she should be moving into her new apartment in a few days, do you think it's best if i stay away from their apartment or what should i do?