Learn English – the equivalent proverb/idiom for Hindi saying in English

hindiidiomsproverbstranslation

Muh mein ram ram bagal mein churi

It means

Speak praise on the face and stab him from behind.

Best Answer

Two-faced

Someone who is two-faced is not sincere, saying unpleasant things about you to other people while seeming to be pleasant when they are with you.

(From the Cambridge Dictionary)

which I think is the most suitable in OP's context.