Oh my gosh - I'm so very sorry about this news
. How heartbreaking for you - I'd just be an absolute wreck.
Was this your regular vet or was this an Internist? It may be well worth it to spend the $ on an office call and see an Internist before making any other decision. They will really know *far* more about your situation than a generalist vet.
If there *is* a chance for surgical removal of the tumor and good survival following removal - then I'd want to explore that further, if it were me.
Please keep us posted and I'll be thinking of you both
!