Hi I’m new here so unsure how it works. I’m just looking for some advice/ help. 
I have a younger teenage brother who is severely autistic and mostly non verbal, every now and then his mother (not mine - we share the same father) gets into contact with me or my dad for different health reasons regarding my brother but is really obsessed with my father. There’s never been any proof of these health issues! She stopped my dad from seeing my brother and it’s not the best situation so we only go off what she wants to tell us and if she tells us. In the past she told us that she had been diagnosed with breast cancer and as far as we know she’s never had any treatment but is now absolutely fine and it’s never been spoke about since until now which she ignores when asked. Today we have been told by her that my brother has leukaemia which me and my dad’s side of the family however guilty we feel not believing but really don’t believe her. All in the space of an hour she needed to get hold of my dad as it was urgent and regarding a hospital appointment tomorrow, firstly it was “urgent he’s really not well and it’s not good” then next “he has got leukaemia and is in third round of chemo” then it was “don’t worry he’s fought he’s not chemo left he’s on medication now and he has got the all clear” then it was “it’s a big appointment tomorrow to see if he will get the all clear”. Between this the appointments have come from hospital for chemotherapy now finished going to a different hospital to have his last review to get the all clear. I’ve spoken to a family member who is a nurse at a different hospital and from her knowledge she doesn’t think there is an oncologist at this other hospital and the difference between the messages all in the same 30-60 minutes has left me and my dads side of the family stunned and we are struggling to believe whether she is being truthful or not, I know that is a huge assumption however due to large lies in the past and when asking for details such as medication or any proof and also failing to notify us in previous weeks/ months until now to say it’s really urgent because he should get the all clear we are all left stunned and unsure how to take the knowledge we have been informed with.