I'm having some big issues with my estranged mom, I need some advice on how to deal with her?

Some back ground, I'm 15 years old. Back in November my father got full custody of me. This was after 6 years of mental, emotional, and physical abuse. Someone finally paid attention to me after she had tried to choke me and almost pulled my hair out. She's hit me, slapped me, punched me, kicked me, pulled my hair. She's pulled my hair repeatedly, called me "dumber than Als*it", "dumb*ss", "dips*it". In fact she's had the audacity to say she was going to call the police and have them arrest me after I tried to hide in the bathroom to get away from her. She clearly has some mental issues, my therapist, father, and step mom, all agree on this, and she wants to meet me every week on sunday because "she loves me". I agree only to spare my dad the expense of going back to court and to get my clothing, which she uses as bargaining chips. Last week she brought up she wanted to talk about the "incident" in November. I agreed feeling uncomfortable about it and talked to my therapist about it and she said to say if i didn't feel comfortable talking about it I didn't have too. Today I attempted to stay away from the topic and told her i didn't feel comfortable talking about it to which she retorted "why? because you caused it". Say what? who was doing the choking? She changes every situation so she's the victim and it's so infuriating! I finally had to walk away because I knew if I didn't I would have punched her, she kept saying it was all my fault and she had taken "responsibility" for her losing her temper but i needed to take responsibility for "being defiant and causing it". I just don't know what to do anymore, If I knew she would move on and stop blaming everything on me I would be ok with meeting her, but that's not the case. What should I do? I just want to know if you've had a similar situation and what you've done. I'm confused and a little angry and i just need some advice on how to face her next week. Thanks!