Stage III at age 26. How do I help my partner?

My parnter was just diagnosed with Stage III colon cancer at age 26. It's been a wild ride the past couple of months. He had surgery last month and begins chemo next week. I'm trying to keep a level head on this, but it's tough. What should I expect when someone goes through chemo? Are they sick for the 6 months they're on it? Also, can someone survive long with stage III cancer? Please, any insight as to how I can cope and understand would be greatly appreciated.
- A 28 year old caregiver looking for answers.