So so sorry I had sex with stranger on break. What can I do now?

Counseling. Talk to someone: counselor, clergy, your doctor, someone who will help you without judgement and without telling everyone you know (i.e. Tell a professional, not a friend).
Be glad you've loved. Embrace your humanity, even life's errors. Whether you talk to a pastor, a professional therapist, a bartender, or your best friend, I hope that (1) what you learn from this experience will make you a safer, kinder person in the future; (2) any health / pregnancy aspects will get discussed with your physician; (3) you will cherish the experience of loving ; being loved, even if it was a mistake.