She was already a contact
Facebook will read your contacts but not your email, if will see and advert in your email and see the same in Facebook this is due to them sharing the same ad provider not them both reading your email, but some email providers will scan your email and give you ads based on that (I think gmail does this), these will probs also show in Facebook (so, I suppose that's indirectly using the email content) . I don't see how they make money from this... I buy a toaster and then for weeks I see my NEW toaster not only in my kitchen making toast I see it on Facebook , in my web based email reader and other websites that use the SAME AD SOURCE. I HAVE BOUGHT THE TOASTER WHY KEEP SELLING ME IT
As for ads, that's normally done with with cookies even if you delete the cookies they can use other tricks to identify you. (google forever cookie and browser fingerprint)
* Use a Punt Phone
* Always use incognito (or private browsing on Edge / IE) for ANYTHING related to punting, eg google maps, search in general, ukpunting , aw etc.
* If you carry your phone with you, turn of location services when you leave the house for a punt.
If you use WhatsApp use a different number as this will also share things with Facebook, I turned of the Facebook share thing on the DAY it was released and I we presented with friend suggestions based on my WhatsApp usage (not punting WhatsApp) Also, just dont put ANY details in Facebook , use an email that is just used for Facebook (I dont do this, but it will make you more disconnected, and less of a profit to Facebook) , dont give it your mobile any details you give to Facebook is used as a point to draw connections this will just grow over time.