my ex girlfriend keeps coming back. i feel like i am loosing my sanity.

[meggy]

hey, i am new to this forum and found some very helpful informations here.
i broke up with my ex girlfriend a month ago, after trying some times before to get out of the relationship because it was so much pain to be with her. she is diagnosed with borderline, bipolar (type 1 and 2), adhd and panic disorder. she hasnt been in treatment for about 5 years and was hospitalized and in medication before. as you can imagine it was an extreme rollercoaster this whole relationship. we ve been together for 9 month and after 2 month she moved in with me. she would let me no room the first 4 month and then starting to be cold, distant and criticizing me and blaming me for every fight. she would constantly tell me how special i was to her and that she never had such feelings for anyone else before. but she would also tell me a lot how incapable i was to really love and commit. and that i need to change in order to save our relationship. i felt like i was doing everything to make her comfortable and i slowly lost my own life, not seeing friends anymore and also starting to be more and more unavailable at work (i am a social worker and i am leading a small institution for drug addicted boys).
after i broke up she would constantly text me that we could process all of this together and she would come to my house at night. she tells me that she is writing a film script about us and our break up because she cant let go of me. every week we get in touch and every week i cancel the contact because i feel like she is trying to keep me in a loop until she finds her new "high". i don't understand why i have such a hard time to let go because the pain just increases every time we get in touch. i feel so helpless and it pains me that i can't protect myself from her. also i feel guilty because she is in such a bad condition. i need to let go but it's so breaking my heart. why does she blame me for everything and then keeps coming back into my life? when will this stop? i am waking up with racing thoughts and a lot of crying. i feel my mental health is in danger.
thank you for reading.