1) you should stop all sorts of self-judgment of any kind, ranging from "I am incredibly selfish" to sky is the limit
2) you should work on the issues of your physiology that has suffered in the past 10 days, as follows:
a) buy electrolyte drinks. Smart Water, Vitamin Water, you name it - read the labels, there are countless brands and you need to choose the flavor you like. Drink drink drink them. It is important to like the flavor(s) because otherwise you won't drink as much
b) (advice off the bipolar forum from a woman who has bipolar and an ED which makes it all worse) - buy V8 and have one can a day. COSTCO sells large trays of small portion V8 cans. Be careful when you buy because V8 now makes some weird terribly spicy concoctions. You need the regular V8.
c) milk and chocolate milk, drink as much as you; tea and coffee - unlimited in the AM, limit after 3PM due to sleep issues
d) dairy/fruit smoothies
e) yogurt, broth, pureed soup - prepared chicken broth heated in a microwave - to sum up, you need to have nutritious liquid or semi-liquid food because when one is nauseous from so much anxiety, liquid nutrition is easier to stomach. I know for myself that 95% of the time when I am so anxious, I can have a glass of warmed milk. Somehow "warmed" matters because when cold, milk feels foreign to the body hurt by emotions. Warmness makes it easier.
f) you need to tell the p-doc immediately that you are not sleeping, are in crisis, and need a sleep medicine ASAP
g) go outside in the morning to get the circadian rhythm back to help you sleep at night
h) 30 minutes outside total, every day
i) walk 30 minutes total (if outside, then takes care of h)), with music if you like

3) register for Google Drive (you will need your gmail address or will need to open a google account of some sort) and learn how to use docs (a blue icon for "document", has less functionality than MS word but more than you may ever need in this lifetime)
https://drive.google.com/

4) in Google Drive (protected by your password, and, MUCH safer than here) create a document in which you will be writing him a letter as you go through the days of your life. Just do not send it.

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Eventually, when you are back to normal eating etc etc you will revisit the idea of actually sending the email. For now, just keep drafting away...