I'm so sorry you're having problems with Crohn's and Diverticulitis. Unfortunately, you can have both at the same time, and many people have surgery for both.
I had Crohn's in my large intestine and rectum for 7 years and had surgery two years ago. I know it's a scary thing to consider, but I have to tell you, I have felt fantastic since being rid of my diseased colon. I also don't have to take any medicine anymore, which is wonderful, too.
I'm glad you found this forum. I didn't have any "ostomates" to talk to before having surgery, so I was completely in the dark. I would have done it years sooner had I known life with an ostomy would be this good. Please ask us any questions you have, and we'll do our best to answer.
Dx'd Crohn's in '99 at 28. Proctocolectomy and ileostomy in '06.
Disease-free, medicine-free, and very thankful to be healthy again :)