First of all, you were treated not once, but twice. A single 1.0
gram dose of azithromycin is curative for chlamydia, as is 7 days of
levofloxacin. In addition, when you started having sex with your new partner (BTW, how do you know she was uninfected?) there was still plenty of both drugs in your system to both be sure that you were no longer infected, that you could not be re-infected and that you could not infect her.