So this girl has herpes and her and her boyfriend had sex in my friends pool with no chemicals in it and i swam in it so is it possible i have herpes?

No: Herpes is not transmitted unless there is CLOSE contact with infected person. First the virus would not survive long enough to infect you, secondly she'd need to have open lesions to shed the virus. If she is just a carrier, she won't shed virus actively, thirdly, she would need to transfer the virus through close contact which didn't happen.