I need advice!

How do I handle a disrespectful mother In law ? I recently found out my husband was doing some things behind my back and she used this vulnerable time to tell me she and her whole family hates me & I'm childish for being in his phone she went on to say she believes nothing I say and prays her son will leave me . Called me bitches and all

Thing is my husband stays in my phone too I just feel like she should mind hers when it comes to our intimate problems.