it depends more on your heart rate and blood pressure, it's what weight brings those to dangerous levels. you're already pretty underweight, and the mental part is the main thing. i was in a residential and there were people coming in at healthy weights who needed to be there just as much as those of us who were underweight. long story short, you need to ask your doctor for what they think, but they only way to avoid being hospitalized is to recover. this being said, hospitals help a lot in recovery