First, I wanted to mention that I (20M) also have autism; however, I am high-functioning and am pretty good at getting social cues and self-regulating. My friend (19F), on the other hand, is not as skilled in those areas. This is all important.
3 months ago, I had a sleepover with this friend at their house, and their mom (52F) asked me if I could pick my friend up after she was done with work because she was busy. I don't like driving to new places, but I agreed because they didn't have anyone else who could pick them up. We decided that in the morning, I would drive my friend to work with their mom, so she could give me directions. I guess that morning, my friend wasn't feeling good because she had an intense meltdown, and when we got in the car, it only got worse. She was yelling and extremely angry over being late to work, which was incredibly distracting and distressing. I was so distracted that I almost rear-ended someone. Everything turned out fine, and I dropped them off safely, but I was very anxious. I spoke to her at the end of the day, and she apologized for the meltdown, but it keeps happening. Another time, she had a meltdown over an unexpected physical therapy appointment during another sleepover. Their mom had texted her about it, and she started crying and screaming at me. It got so bad that she was throwing things and saying, "I was going to leave her, like everyone else." After she calmed down a bit, I helped her get to her physical therapy appointment. These incidents have made me anxious, and I'm not sure if I want to keep being close friends with her. Her mom seems to think I help them calm down and asks me to help them go to appointments and hang out with them during stressful events. I'm starting to feel like a glorified caretaker. I want to kindly step back from the friendship and communicate my grievances without my friend feeling like I am abandoning them. Any advice would be greatly appreciated.