My sister has anxiety along with IBS and has had many of the same feelings you are describing. She has also had employment problems around the bowel issue but she is currently working and doing pretty well. She is single so not working isn't an option for her.

My sister has a funny story, though. She was in the local grocery story and had to use the bathroom there - a huge attack of IBS that she said wasn't pretty. Next time she was at that store they had completely remodeled the bathroom and she wondered if she was the cause

I don't think it is possible to get the anxiety fully under control before you return to work since working is a large part of your fear. The act of going back to work and getting through it will ultimately diminish your fears and that will take time and effort. Some acceptance of your condition and who you are is part of the 'work' ... IBS does not make anyone a bad person ... just someone with an overactive bowel.