NC so not related to other posts .
Background :
Two years ago my mum passed away . I found out while going through finances with dad, my brother had conned them out of literally thousands over four years . His partner ( we will call her Mandy) then split up with him for various reasons - including this.
Dad sunk into a deep depression and is very vulnerable. I see him a couple of times a week and call him daily . He said that Mandy's car had broken down and she'd asked for 2K to get it fixed . Non of my business, if she needs to get to work / ferry kids about then fine .
Yesterday , she said she was going to take the kids to see dad . She turned up late and texted me as he wasn't in and he never rarely goes out in the evening . I said he'd gone out with friends for dinner as I'd spoke to him that morning .
Mandy said the back door was unlocked ( that's normal as he forgets to lock it) so she went in to check if he was there and ok.
At this point , I just asked her to lock the back door and let herself out the front and thanked her for checking etc .
30 seconds later , she texted that she was trying to log into dad's on line banking to 'check he'd sent the money '
I felt panic rising and told her not to even try and to leave . She then texted ' I feel gross now and I'm leaving '
We've not had contact since . As far as know , she didn't get into his accounts . I haven't told dad as he's having a bad day today mood wise and is very tearful about being alone , wishing mum was here , he has nothing to live for etc .
What shall I do ?