I'm a bit confused. exBIL is prretty clearly a covert narcissist (obviously with the rider that's our diagnosis, not clinical etc - but he has many of the traits). SIL was, obviously his victim for a very long time.
Theoretically, she is still his victim - he's manipulating her and using a lot of the usual tactics of guilt and all the rest to get her to agree to do things that are ridicujlous.
BUT.... she also seems to be his flying monkey in that she's now in big fights with his family who have all refused to have anything to do with him because of his behaviour - she thinks its outrageous and is alternatively either arguing with them or telling them they need to offer him practical/financial/emotional support.
She also appears to have stopped seeing his behaviours as problematic but instead has moved to seeing them all as being entirely out of his control due to mental health issues and trauma.
It's very confusing. We're keeping far far away from it all. But I do worry about the long term impact because one of the things that was a big concern whent hey were still together was that he tried very hard to drive a wedge between her and her family and also, simulataneously, to get her family to support him. And now that he's managed to wriggle back into her life (not as a partner), this new thing where HE is the victm and she's 100% convinced it's purely these other issues means she's withdrawing because she knows that we don't approve of him and that was bad before, but now that she seems to be thinking that he needs support, this is worse.
There's loads more but I wont go into it. But I suspect there's goign to be a showdown between her and DH at some point (not becuase he wants to but becuase as is always the case when ex is in her life, she will do/say/ask things that are completely inappropriate on HIS behalf, and eventually DH will have to say "NO").