No need to panic
Statistically, One in 100 to 1000 unprotected sexual exposures can lead to transmission of the virus. A single act need not, but can, infect you. Testing is the only way to find out.
PEP (post exposure prophylaxis) can substantially reduce risk of transmission, if taken as early as possible, but not later than 72 hours after exposure. Consult a doctor or call the helpline
HIV infection does not mean imminent death. People living with HIV and AIDS can have a near normal life and lifespan.