I might have worded the title a little weird but I'm not much of a writer and couldn't think of the best way to fit the situation into one sentence, so I'll make sure to explain it better. When I was around 8-ish (I'm 17 now) my mom met this guy who she really liked I'll just call him S. He had a daughter (I'll call her A) who had some developmental issues but she is pretty high functioning and she was seeing counselors/psychiatrists (I'm not sure specifically which) regularly. My mom and S hit it off and eventually S and A moved from their house, owned by S's mom at the time, to our trailer house. There were a few small issues from time to time especially with S being frustrated with my brother (around 4-5 at the time with similar issues to A) and was extra strict with him. After like a year or two S's mom, who was pretty much the only mother figure in A's life, passed away and both S and A took it really hard. All 5 of us (and our cat) moved into her house and lived there for like 5-6 years with little issues between me S and A. In like 2020 or 2021 we moved all moved to a completely different state (for reasons I'm not 100% sure of, they mentioned political reasons fairly often but idk). The move was difficult for all of us, all of us kids had to leave behind friends we knew for years that we probably wouldn't see for a long time, the house we moved to was cheap with the money my parents earned in our state but the only jobs nearby offered significantly less pay, and all of us were finding it hard to acclimate to a completely different landscape and climate (politically and geographically). My mom took it the hardest as she found it hard to find friends and she is a very active person who hates to just stay at home, but there was nothing to do there. We lived there for another couple years and in that time tensions were really spiking between my mom and brother, and S and A. My mom and A were constantly getting into arguments where S would jump to A's defense and wouldn't support my mom and S would be strict on my brother (I honestly thought that was a good thing for him because he was like 8 or something and couldn't unload a dishwasher) and my mom would defend him. During all this I was stuck in the middle because I had very good relationships with everyone and I could see this split in my family growing with everyone coming to me to talk about issues they had with each other. I figured we would persist through these issues because they had been around since the day S and A moved in but they were just a little bigger now. Another point of dispute between S and my mom was that my mom worked for the local hospital (this was around 2021 so that super sucked) while S worked as a freelance electrician so he was at home working on taking care of us and maintaining the house often while my mom was at work. After only like 2 years we decided to move back to our original state because my mom and S couldn't keep up with expenses. We spent a night in a hotel while we were moving and some dispute ended up with S and my mom going out into the hallway to talk. I listened through the door and heard them bring up the idea of splitting up before they went down to the parking lot to finish. I told my bother and A and my mom and S came back into the room to find all of us on one of the beds crying together. They told us that they did decide to split and that instead of all of us moving into one house, S and A would find their own house while my mom, my brother, and I would do the same. My mom and S found a small place that was right for S and A and we decided that we would all live together there while we found a place for me, my mom, and my brother. On the first day there we were unpacking and I wanted to change my clothes because I had spent a couple hours in the hot sun unloading and I was sweating like a pig. I went into A's room with my backpack, locked the door, and started changing when I heard knocking outside and A telling me to get out of her room. I finished changing (it only took like a minute tops) and came out to find S had come over to see what was happening and S was complaining to him. S decided to bring everyone but A outside and told us that this was S and A's house and that he wanted us to treat it as such while we were guests there. This set my mom off and she said we wouldn't stay there so we went back in to collect our bags and leave. While I was grabbing my things, A came and apologized to me for blowing up and asked what happened, I told her and we said goodbye on good terms. Me, my mom, and my brother ended up in a motel for around all of summer vacation until we found our current house. My mom and S's divorce was messy and S started drinking because of everything that had happened. We've been living here for almost 2 years and I've stayed in contact with A and if S is around when me and A call, I'll talk to him too. We mostly text and just talk about whatever but we do call sometimes too. Recently I've been talking to A more often (from calling her once every month or so to once every other week) and this is where the problem comes in. Last night I was on the phone with A when my mom came up to me furious. She mouthed for me to do something but I couldn't understand so I took my earbud out and clenched it in my hand so A couldn't hear. My mom told me that if she found out A was bad mouthing her she would make us cut off contact completely. I thought this was weird because me and A have almost never talked about her and on the rare occasion that she does come up, A would say that she misses my mom despite their issues. I told my mom that we hardly talk about her and when she didn't respond I went back to my room. As I was walking back, my mom told me to hang up and come out to talk, so I went to my room to grab my phone and hang up and I went back to the kitchen. My mom told me that she was upset with me talking to A and S and that she wanted me to cut ties with them. She went on to tell me that it is messed up for me to keep talking to them when they hurt us so badly. I told her that they didn't hurt US, they hurt her and that I was in good standings with them before and after the split, especially A. She got even more upset and told me to do whatever I want and ignored me for the rest of the night. I haven't seen her today so there hasn't been a follow-up yet. I really don't want to cut contact with A or S because they've been my sister and father for the majority of my life, I can hardly even remember a moment where they weren't with us. Another reason I stay in contact with A is because we have so much in common, we like the same shows, games, books, and activities, while I don't share any of these interests with my brother or mom. A is the only person who actually wants to do the same things as me. A is also one of my only friends, I met some people at school last year but every one of them graduated or changed schools and we've lost contact, and everyone from before our moves have stopped talking to me. If it weren't for A, I would have zero social life. As I write my feelings down I feel more and more in the right but I would like to hear some other perspectives. Thank you for struggling though my writing and for any of your thoughts. ♥️