When someone in the family is living with mental illness, adult or child, everyone needs support. Silence and secret keeping will come back to haunt you. There's nothing shameful about talking with a therapist or counselor. Maybe just once, maybe on a regular basis. There's nothing to be lost and the world to be gained.
When facing the emotionally trying experience of eating disorder recovery, being physically close to someone that you have a positive relationship with can help to alleviate stress, and the oftentimes powerful negative emotions that come with it. Load sharing is exactly how it sounds: you are simply sharing the emotional load.