Devil within

I just found out that both my bonus daughters hate me to the bone. My partner and i have been together for 7 years now. But we were a couple for 10 years. He has 2 daughters, age 15 and 13. The eldest is now with her bio-mom for vacation and the youngest chooses to stay with me. The sisters were chatting a lot. Which is a good thing, i thought. One time, I got curious coz it seems serious, coz the youngest keep frowning while chatting. I asked here nicely if she's ok and who's she chatting. She answered "nothing". "You will regret this", i warned my self. Yet I continued. My youngest bonus daughter went out for a walk with her friends. She left her gadget, charging. ... Yes ... that's what i did ... I open their chat box and I discovered that they were talking about me. They were cursing me in chat box while the kid is looking at me and preteding that nothing is wrong. I took care of her for 7 years, she was so sweet and honest. We were so close. Some said that I'm more of a mother to her than her bio mom. That is why i was so shocked. She said to her big sister that i made her head hurts. I keep joining in every conversation which I'm not part of (while the four of us were a having dinner). That they don't ask for my opinion nor needed one, yet i talked a lot. That i didn't give her money for her parcel ( i can't remember she asked me). I complain a lot even though I'm not part of the conversation.  She also said that their father is having a sad moment few days ago and I contribute to it rather than make him feel better. That i always asked them where they're going with whom. I also read her chat box with her bio mom. They were both laughing and cursing me at the same time whenever i made a fool out of myself. Whenever i use high tone on her coz of my migraine. My chest hurts learning about those conversations. I am a college graduate.  I decided to live with my partner few years after i graduate. I worked in different companies. I stopped working coz i always dreamed of being a good housewife like my mom. I wanna take care of my family since my partner can provide for our family. I never asked for anything, just for them to respect me. I never dreamed of replacing their bio-mom (which the kids defined as not acting her age and acts like a childless teenager). But whenever i made a bad decision, i said a wrong word, they run to their bio mom like I'm the worst person in the world. Cursing and laughing at my mistakes. Even though i keep on asking for their forgiveness and explaining why I did that or said that. Sometimes i overheard them mumbling. I joined parenting groups, read books and articles about parenting coz i want to be like my mom. Understanding. Strict but never hated. I believe no ones perfect. But the fact that they respect and talked to their dad nicely, online and offline, and hate me to the bone makes me feel like there's a devil inside me that only the 3 of them can see. That crushed my heart. #bonusmom #stepmom