Have you ever experienced paranoia and obsessions?

I wasn't able to help my girlfirend with BpD.

She was and still is obsessed with people, particularly with my sister. A negative obsession, such that for a year and a half, every day’s crises were caused by my sister and how, according to my ex: "I was her puppet, that I loved my sister more than I loved her, that my sister was a burden to us"..

Finally, my ex left me because of my sister or she left me cuz she was convinced that I was leaving here choosing my sister.

She was convinced that for the four messages I exchanged with my sister, I was scheming behind her back, dedicating all my time to my sister. When, in reality, it was only four messages a week. So, when they saw each other for 4 days every 2/3 months, they treated each other badly, which only reinforced the cycle of paranoia.

A paranoia and obsession with this person, to the point that my ex’s reality became her own delusion: she was a lawyer from a very wealthy family, while my sister worked in fast-food... She wouldn't listen to reason, even when I told her that my sister wasn't a threat and that we should focus on our relationship…

She demanded that I throw my sister out of the house and "torture" her to make her suffer as much as she was suffering herself…

Which house? Thah's the tragic part......Me and my ex were living in Milan, my sister was living in Venezia, with my parents, something as 500km away from us.

She forced me to share negative and personal details about my sister and then used them against me during her outbursts.

I have tried all methods to convince her that my love and my dedication were pure... According to her I'm a moster for what i did to her.... namely chose my sister.