Ciascuno,
Sorry you are in this spot. Now, time to get with it. You can do this and so can your Mom. I fully believe that one of the best things to already happen to your Mom is they didn't remove her stomach. It is so hard to recover any fighting weight without a stomach. Now that she is starting chemotherapy, one of my first recommendations would be that she get a port installed. It will make her treatments so much easier.
How so I know these things, you are asking. My partner of almost 25 years now has been fighting this terrible disease for over two years now, Stage IV, inoperable. Tomorrow will be his thirty-fourth chemo treatment and it has given him his life back. While we will be moving to his third line regimen tomorrow, the treatments already done have let him maintain two years of INCREDIBLE QUALITY OF LIFE. We were in the same spot as you are now two years ago. Really, it has been such a blessing. At first, we didn't even think he wanted to get started, now we are overjoyed at the quality of his health (no appreciable side effects at all). You know, at first we were looking at 6 to 8 months. It has been a very good two years.
I know you are in a terrible pickle, but pick yourself up, and know that you can and will help your Mom through this diagnosis. Her life is just changing a little bit (a lot really), and with some positive attitudes and life saving treatments, she can get back to feeling better. You CAN do this.
As questions come up, make sure Mom can tell her oncologist every little thing. They can adjust dosages to minimize any side effects. Any other questions that come up (and they will), depending on which drugs she is using, feel free to ask them here. There is a lot of experience and people that have gone down this road ahead of you. They are available to you as a resourse, use it.
In the meantime, be thinking a little about "The Bucket List", there might be some things on Mom's list that she needs to get done, just in case.
Thoughts and Prayers to you and your family........... Scott