Your period is late. Your friend-with-benefits or special-handshake relationship wound up staying a night or two, as Todd Rundgren sang in his classic 1970s hook-up song, "Hello It's Me." So unless the pregnancy test is a false positive, chances are you're pregnant.
Expressions of hurt and anger might arise as if by instinct in you. You blurt out to heck with what's-his-face, the sperm-of-the-moment donor. It's scary to face the fact you could be signing up for a life of co-parenting with someone who is virtually a stranger.
Brace yourself for some rockiness. Being parents together is one of the most intimate and challenging endeavors under the best of circumstances. Accept with all the strength you can muster that it will be difficult to do this with someone with whom you have very little shared history.
First, know that you are not alone. There are more new moms and dads like you co-parenting in this context out there. While the stigma of single parenting is abating, except for the highest earners and most privileged among you, the challenge to make ends meet has never been greater. This alone will require a baby's parents to interact.
Baby will need both parents' financial and care-taking support, even if friends and family are available to help. Don't kid yourself about this. The "I-can-do-it-alone" attitude might last part or all of the pregnancy, through moments both high and low, when you-against-the-world is up for the challenge.
Other times you wobble in your resolve to go it alone. Putting the financial and care-taking assistance on the back burner for a moment, the impulse to reach out to share your news and the experience of parenting is part of what it means to be human. You can't avoid it.
Even if you move away and cut all ties, chances are (with the Internet, it's nearly impossible to hide) that eventually the baby's father will enter your child's life.
In promising to protect this new sentient being, double-down on the vow to make room for the "other" or back-up parent with the caveat that you calibrate your expectations to the fact that he (or she) will always be a disappointment on some level.
Get used to holding your nose metaphorically speaking because of the required taste it takes to going along to get along with someone you can hardly call your ex because you weren't exactly ever "on."
Be careful not to demonize your co-parent. Remember you two didn't just collide. On some level you chose each other; albeit not as carefully as you might have liked. But unless there was a gun held to your head or your arm was twisted, you were likely engaged in a consensual if not particularly conscious relationship.
Forgive yourself. Fight-to-the-end attitudes only hold your child hostage, keeping them trapped in the middle and in the long run, might likely snap-back and work against you in the end.
Remember forbidden fruit can be powerfully motivating to a child who doesn't have a clear path to a less than full-time or absent parent. Learn instead to yield to this phase in your evolution, healing old wounds along your path.