After I split from STBXH I realised that he was a narcissist. To be honest, he'd told me as such when we were together but didn't know what it meant and he seemed quite proud of it so didn't give it too much thought 
Anyway, since splitting up his behaviour has been truly terrible. Mind games, threats, then "I'm only acting like this because I'm so confused and sad". I've been NC for a couple of months but due to the imminent sale of our house and having to discuss our financial settlement we have been back in touch for a couple of days.
I don't want to go into too much detail as it is very identifying but he is being very nice and reasonable at the moment. He is playing down one part of the financial settlement because this is what he clearly wants me to agree to while making a very generous (but money small) offer. He has also started gaslighting me. I know what he is doing, I know it is bs but each time I react to it and check myself to make sure I haven't done what I have been accused of - even though I know I haven't! Can anyone give me any advice on how to deal with this?