Forsake is generally used in literary texts but not often in everyday speech, and you will hear it most often in the reference to Jesus on the cross, crying "father, why have you forsaken me".

Forsake is a word that isn't used very often. It means to abandon someone, often by betraying them and hurting their feelings. It is only used in older English texts. Leave means to move away/go away from someone. This word is used a lot and it can have both good and bad connotations.