What was Yaakov really afraid of? How does Yaakov's fear, save the Jews in the times of Purim?

Sources:

Midrash Rabba Parsha 76 Perek 1

Bereishis Parshas vayishlach Perek 32 Possuk 8

Commentary of Rashi on the Possuk

Commentary of Sifsei Chachomim on Rashi

Sefer Maayono Shel Torah Bereishis page 145

Gemara Gittin 56 A and 57 B

Gemara Horiyos 13 A

Commentary of Tosafos to South 12 A (Acherim Omrim)

Gemara Sanhedrin 98 B