You're not going to say anything because you're not going there again, buddy!
If you do ever go in there accidentally, make sure there is a nice looking girl with you whom you are giving all your attention. As for the "old love", just pretend you've never met her before and behave that way.
But even that is lame. Better to be seen with that new girl somewhere other than the pizzeria.
In a girl's mind, the most plausible explanation for your appearance, location or behavior, should never be that you have some premeditated plan to enter into her presence.
If you show up at the pizzeria where she works, no matter who you are with, the most plausible explanation why you are there will always be that it's because you are thinking of her. Thus, you shouldn't do that.
You can still create a situation in which you can approach her, but it looks like a chance meeting. But again, create too many of such situations and it looks like you are stalking. Bump into her once or twice in a span of sevearl months, and the most probable explanation is that it's coincidence. Bump into her five times in four weeks, and coincidence is not longer the probable explanation!