Hey there,
So from your post I understand you have had Crohn's symptoms for the last four years? It sucks to live miserably, and not have a diagnosis. How did they actually diagnose your Crohn's (normal route would be via a colonoscopy with biopsies of tissue samples, blood tests for inflammation markers and a differential diagnosis taking your symptoms into account)?
In any event, informing yourself about Crohn's is definitely the first right step to get it under control. Diet is only part of the puzzle to get it under control, have you talked with your GI about long-term management? Normally if you got inflammation and not just very mild Crohn's your doc would suggest either immunosuppressives or biologics (or in some cases a combination) to get you into remission (symptom free).
As to diet, unfortunately most Crohn's patients have made different experiences. There is a golden rule for most, which is that everything which goes towards a certain extreme isn't good - that is, if you eat too oily, too spicy, too salty, too sour, too sweat etc. foods. Or in other words, neutral taste is normally considered good. There are many threads on this forum about what people eat and where they have problems, I'd recommend to search for them and just read a lot to get an overview. With Diabetes you are already confined to certain foods, but to be quite honest, anything that would get your blood sugar completely screwed up would probably also get you in trouble with Crohn's.
I can tell you one thing, it might take a while and take some effort (and getting information and a good GI etc.) but you can definitely get Crohn's under control and get back to living a very normal, good life without any pain or problems.
Cheers,
A