Long story-DB has my mum's email account stored on his phone and I gather she knew about this as he sometimes helps with her online banking. SIL was using DB's phone and snooped on DM's email and read a recent one which basically said she hated SIL and her family and that DB marrying her was a curse. DM is a toxic mil and has been awful towards her, she hasn't liked her from day one and is openly critical. I've always stayed neutral and got on with SIL and pull DM up on her behaviour when I witness it.
SIL is furious about email and so is DB . its like the last straw..she wants NC with DM which is understandable but equally she was in the wrong for snooping. DB told me he doesn't want DM to know she saw the email but that SIL wants nothing to do with her now. I don't want to take sides but I'm so angry with DM for messing up the relationship. I don't know whether she needs to be told that her email is the cause..so confused :(