I don't have an ED but I do have phobias related to food so I also have rather abnormal eating habits which have actually gotten A LOT worse since I started therapy.
I felt ashamed for it too for various reasons. 1. how stupid is it to be afraid of food??? 2. I go to therapy to get better and what happens? I get worse so I feel ashamed because I feel like I'm not working hard enough. Blaming myself for everything.

I guess with SI it's the same thing. You get "weak" and let it happen or make it happen even though you know you shouldn't. I think it's very similar to when kids mess up and have to come clean to their parents- the people who (should) know better.