Oh, Kat. I'm so sorry. Thinking of you and your sister and I will keep him in my prayers.
I'll post a positive anecdote. My cousin was diagnosed with bladder cancer about 10 years ago and his original prognosis was guarded, but he's still here and living a full life. Treatment wasn't easy and they had to build him a new bladder, but he's alive and well years later.
Sending lots of hugs. I'm so sorry. On the positive side, my uncle and my brother in laws father both had bladder cancer and got new bladders and have done well with them for quite a few years so far (I think 7 or 8?) Hugs again!