Hi, WFS.
I'm pretty much new here so I don't know a lot about you, but my father has been diagnosed with cancer some months ago so I hear you there. If it's diagnosed on time, the prognosis usually is good. And having the kids to fight for, I'm sure he will fight with all that he has in order to overcome the disease.
If you wish to talk about it, you can send me a message.
I hope that it all turns for the best for you, your kids and their father.