Tinaelise,

You're not being selfish. You're reacting in a very normal, caring and loving way. As you already know, you will get a lot of support, comfort and help from all of the wonderful people that participate on this site. What I can share with you from my experience as a caregiver is to take a deep breath each time that you feel overwhelmed. I know it sounds corny, but I took this advice from others, and healthcare professionals, and it helped me maintain my composure as best as possible given the circumstance. It kept me from flying off the handle on several occasions. Everyone recovers differently, but of course there are alot of similar experiences during the treatment and recovery process. My mom had her lymph nodes removed as well, her primary site was on the inside of her cheek. We got through each stage of the treatment by knowing it was all part of the process. Removing the nodes was just one of the steps that needed to be done. Your mom will always be the loving mother and grandmother that she is, that will never change.
If I could give you any advice from what I've learned over the past year and a half, it's to try to remain as calm as possible. I know it's not easy -- hell, I'm the poster child for being neurotic, but if you can keep yourself in check, or as close as possible, you'll be able to better manage each day.
All my best to you and your mom,
D