How was the abuse your fault? (Sorry, blunt question there, couldn't find a better way to phrase it!). Abuse is never the victim's fault.
In terms of the stomach issues from your eating disorder, whilst in a way it can be helpful to think "I need to improve my eating so I can have less stomach issues", I don't think it's helpful to say it's your fault- it's not your fault that you have an eating disorder.
Is your GP/team aware of your stomach pain at all? If not, once you're ready, I think it would be a good idea to let them know, as there may be something that can be done to ease it.