This is a great question, because Oedipus' interaction with people says much about his character and consequently this tragic flaw. First, it is important to note that his negative interaction with people grows gradually throughout the play. At first he is simply a good and responsible leader, who wants to help his people during a massive and destructive plague.
Second, we are able to see his interaction with people best in his treatment of his wife/mother, Jocasta. Even when Jocasta tells him repeatedly to stop his inquiry, he does not even consider it. Even when she begs, he is completely insistent. In this sense, he is proud and his pride drives the movement of the play to a tragic end.
We also see a harsher side of Oedipus as well when he talks with the shepherd who saved him as a baby. When the shepherd is hesitant to talk, he threatens him with torture.
One final example should suffice to show Oedipus's odd blindness. When he hears that Polybus, the king of Corinth is dead, who he believes is his father, he is filled with happiness. He even says, "Polybus / packs [all the prophecies] off to sleep with him in hell!" All of this shows that people matter little to Oedipus.
These vignettes show that Oedipus for all his great qualities possesshubris, which is his tragic flaw. In a word, his pride is great and knows no bounds.