Thanks for your replies. It hasn't really sunk in, she bounced back from this operation earlier in the year so well we really thought she had a good 4-5 more years in her. She's very chirpy though, being allowed to do what she wants.
Its so sad

they don't understand and you just feel so cruel
TBH haven't thought at all about the next stage, just trying to come to terms with the prognosis at the min, and hope that she has more than a month. Not sure how accurate the vets can be with this?