Partner has oesophageal cancer

Hello. My partner was diagnosed with oesophageal cancer last September, we were told that is was too advanced to do anything about it and it had spread to the lymph nodes. The oncologist said he could have about 15 months with treatment. He is coming to the end of chemo treatment, which has really taken it's toll on him, he has been gettting incredibly anxious and sick at the thought of having chemo! He has another 2 weeks left of radiotherapy. He isn't eating much because he's lost his appetite and is retching a lot. It's heartbreaking watching him go through everything and knowing there's not a lot I can do to help him. We are due to marry in May and have 2 children (ages 9 and 7). I can't imagine living without him, he is my rock, my best friend. It's been a tough almost 6 months already and I know it's only going yo get worse, I'm so scared, I don't know what to expect and I don't know if I'm prepared for what's to come.