DO give yourself time and space
There's no way around how shitty this situation is. And for a while, your roller coaster of fucked-up emotions will make Kingda Ka look like the lazy-river log flume. One minute, you’ll be overwhelmed with how badly you never want to hear from or about this person again. The next, you’ll miss your partner SO MUCH and be unable to fathom life apart. This is where that magical concept of time comes in. Give yourself well-deserved space from your partner until you’re ready to reach out and discuss next steps. In the meantime, do what makes you happy. Write, exercise, bake cupcakes, go noodling (I dare you to Google that). Careful with the drinking, though -- booze is a scientifically classified depressant -- and poor-decision-making guarantee.
DON’T deal with this alone
Dionne Warwick nailed it with her 1987 ballad about what friends are for. Don’t be afraid to use them! Call them, meet them for lunch, have them over for movie nights, and let them take care of you. But not forever. Relying on your buddies too much may strain your friendship. One late-night emergency phone call is fine; a week of 3am rants is not. These people aren't trained (or paid) therapists, who, come to think of it would actually be PERFECT to talk to. A little professional advice and some well-thought-out coping mechanisms can do a world of good.