Crohn's and relationships

I was diagnosed with crohn's three years ago and have been going through the ups and downs of lifestyle changes and medications to control my symptoms. I have been able to identify stress as a large cause to my flare up's, among other things, however this seems to be the greatest. I know stress is apart of everyday life, but ever since I told my fiance' that stress is a large factor to my disease he seems to be stressing me out more and more without making any effort to a resolution. I do what I can on my end, staying calm, breathing techniques, etc. but he does not seem to get it and I do not know how to get through to him. He even goes as far to say that I am using my disease as an excuse. I do not know how to speak up with out making it an excuse as well as to look out for my best interest and get through to him. Please help.