Hi Jenny, you absolutely have the right to feel this way, and much more besides. Good on you for sticking by your man. My husband was diagnosed with non-Hodgkin's lymphoma in 2011, and had 6 months of chemotherapy. The one thing he said most often to me after the dust had settled was "Thanks for being there for me". Regardless of how calm, stressed or even soggy with tears you are, your support will help, so don't feel bad about feeling bad.
I'm glad you found this forum, too. It's a great place to vent and get encouragement, as we all try to help each other through everything that cancer throws at us. Sending big hugs, Emily