J was there and we wanted to have a chat between the three of us to clear the air. I thought it went well, then afterwards S said that I was constantly talking over her. I really didn't think I was, but if I was then I'm sorry - I am borderline aspergers (I have many traits) and I struggle to know when it's my turn to speak in social situations. S concluded from this that I was clearly putting J ahead of her in terms of my priorities - to conclude this really annoyed me and I tried to reassure, it didn't work and I snapped a bit.
Can you not see everyone since youve posted have said the same thing? The above quote is her manipulating you into believing that you are incapable of maintaining multiple relationships. Even when you think you're being reasonable, mature and fair as you have been, she tells you that you fucked up. You treated her badly as soon as another person was even remotely involved. I'm going to say this in another thread too but what a therapist told me when I was about 14 was that it is fine for me to have an anger management problem. I can keep it if I want. What I don't get to do is harm other people with it. And that is the same for anything: it's fine to have emotions, to have insecurities, to have issues, but when we project those issues onto other people in a way that harms them, that is unacceptable if you want to have healthy relationships. When you identify that you are doing that. You stop. No mater what you have to do, you stop that behaviour. You learn about why you do that behaviour once it's stopped and your feelings will "catch up". But first you stop harming.