Chris,
I know I'm very late to this discussion as I am just now getting back to GTPlanet after a couple month absence.
It seems you've gotten some great advice from the guys on the thread already. I'm glad you got things cleared up that it's ovarian cancer and not prostate cancer that your Mom is suffering from.
The only thing I can say about cancers is that different cancers have much different prognoses and treatment options. It's very good that you have gotten with an oncologist now, because as the others have said, these are the cancer specialists, and going through the ER isn't always the best option. It sounds like your Mom's treatment is in good hands now.
I would also echo the advice of the other guys here to take good and detailed notes about what the doctors tell you, but it sounds like you are already doing that.
Finally, I will tell you that cancer does indeed suck! My father passed away from prostate cancer several years ago, so I have an idea what you're going through.
On the personal side, I will tell you this. When I learned of my father's diagnosis, my initial reaction was both shock and sadness. In my father's case the disease had already progressed to the point that it was just about treating it the best they could with radiation and chemotherapy and then managing his quality of life. Unlike pancreatic cancer which moves and kills very quickly, prostate cancer moves more slowly, so in my case it was 2 years from my father's diagnosis until his death. That first year when he was still mostly healthy and not super weak yet, we took full advantage of it and had some of our best times together. I took him to New York to see the US Open Tennis tournament, and it was one the best memories I have with my Dad.
I don't want to sound macabre, I don't know your mother's prognosis, and even the oncologists will tell you estimating survival rates and duration is a fairly inexact science.
But the point I'm making is this. Don't worry about the pieces of this you can't control. Just be there for your Mom and pray for her well being. In the best case, maybe she can kick it, but if it really is stage 4 as you say, the prognosis may be similar to my father's. Ask your oncolgoist about this. The other thing to ask about is whether the cancer has mestastisized to other parts of her body. This has an impact on the treatability and prognosis.
Regardless, in the worst case if she has limited time left, savor every moment of it, and do your best to keep her comfortable. It sounds like you're already doing that.
Prayers are with you and your family.