Self esteem is always a really hard issue. It's one thing to say, "Be happy you're alive; this saved your life," and it's another thing totally to actually feel it. I have a (hopefully) temporary colostomy. Complications from my colon cancer treatments 4 years ago led to an ulcer which wouldn't heal, became infected, and ultimately perforated, causing acute peritonitis and the colostomy to stop wastes from flowing through that part of my colon. Definitely a life-saver, but I was NOT looking for that kind of solution! A lot of rebuilding your self-esteem is friends and family who are very accepting and supportive. Also, there are a lot of products (belts, wraps, etc.) that help hide the presence of the pouch, and help you feel more normal because you look more normal, and can ignore the presence of the appliance and go forward with your life.
Make sure the doctors are very frank with you, and write down all your questions and bring the written list with you to your meeting with doctors. If you don't ask, you will always wonder if there was another alternative that wasn't explored. Also, as you talk to the doctors, make notes on pros and cons of each procedure they are considerig - pros and cons as they apply to YOU, not just to them. They do want what's best for you, but they are mainly thinking straight physical effects, not mental or emotional effects of the procedure.
After a while with the ostomy, you may also decide not to get it reversed, at least not right away if it means a second surgery for an ileostomy as well. The reversal, as well as the ileostomy, are both major abdominal surgery, and will take time to recover from each. You may also want to see a counselor who can help you with some of the emotional effects of your surgeries. Good luck and good life to you, whatever you decide - you still have lots of good life ahead, either with or without the ostomy!