Tell her! When you are about to sleep with someone you are comprimising your body. She and anyother woman deserves to know you have slept with hookers. I would want to know. It is her decision to sleep with you after she knows you have been with a hooker. Even if you got tested afterwards.
though this message seems old I'll still reply on it:
You could also choose a middle way: say you never had a girlfriend but aren't a virgin either. so still lots of room to interpret. But in any case get tested...
