bfs ex gf

so i need some major advice. my bf has this ex gf from like 4yrs ago. she is a crazy ass bitch. no joke. his whole family hates her. she got in a new relationship like right after she and my bf broke up. he doesnt have any feeling for her anymore and we have been together for almost 7months now. i love him and we have talked about moving in together and getting married. problem is i hate him ex gf. she will call him like 5 times in a row. text him. he tells her its not appropriate and hes in a relationship and loves me. he still cares for her as a friend because she has some sort of like mental illness and her bf got her hooked on heroin and knows she could die soon. i have a HUGE problem with her and the fact they still talk. my parents hated my bf for a while because of a pic she posted of them 4 years ago on facebook. i dont know how to tell him i dont want him talking to her without driving a wedge between us and me coming across as a bitch and losing him. im so confused about what to do 😩😞