I wondered if Lydia had abruptly ended her "friendship" with Javier would she have suffered consequences. Javier made his feelings known to her. Could he have threatened Lydia with harm against her family if she had rebuffed his friendship- -before he actually DID harm her family? It is possible, knowing how Javier felt, that Lydia believed continuing their friendship would protect Sebastian.
But WHAT WAS SHE THINKING when she picked up Lorenzo's telephone outside the cave- -so close to the rendezvous point with the RV- -and called Javier on the telephone??? All I could think of was that Lydia's holding up of the group at that point in the journey (to call her family's killer no less) was going to jeopardize the safe arrival all of her fellow travelers. They were all going to get caught because of this unnecessary and stupid action. She took so many precautions- -leaving the car, not using a bank machine, securing Luca onto the train with canvas straps but then called the man who was hunting her??? No way!