what do i do?

my boyfriend and i have been together for a little over 10 months now and we’re doing pretty well. he has an ex tho. i don’t have a problem with my SO having an ex bc that’s normal but she’s very obsessive. they’ve been broken up for over a year and she won’t stop talking about him. she even sent him a love letter about how much she misses him. they only dated for 3 weeks and he doesn’t feel the same at all. he has her blocked on everything but she even tried contacting his friends once. she hates me for the sole reason that i’m dating her ex, who was my best friend prior to them dating. while they were dating i had completely left his life bc she was so insecure of having me around and i was fine with that bc i respected their boundaries but she has this idea that i’m the reason they ended things. now over a year later since they’ve been together, she still posts about him on her tik tok, makes comments, talks about him, tries to get to him and wants to do all that she can to get rid of me. i know my boyfriend is just ignoring her and as am I but still seeing the things she does is unsettling. how do i change this for myself? it gives me anxiety even though there is not reason for it to. she means nothing to me or my boyfriend but after all that she’s done to ruin our relationship and the fact that she hasn’t gotten over him yet just bothers me. she also apologized to me for everything a few months into our relationship and 2 months later she asked my boyfriend to cheat on me with her, so talking to her about it is out of the pocture. i just want to leave her in the past.