One step at a time my friend. I forget from where it was, but someone pointed out the main difference between introverts and extroverts like this:
As an extrovert, you start your day with 0 coins and you have to collect coins. You collect coins by interacting with others.
As an introvert, you get an x amount of coins at the start of the day and each interaction with others costs you a coin.
And I feel you about pretending to be fine as well. For me it helps if I can at least talk to one person about it during those "dark" times. And that person doesn't even always have to even be actually real (imagination goes a long way hahaha). But everyone has their own methods of applying self-care.