felling angry with hubby

I feel soo... angry with the hubby to night just found out he been txting my sis in low and my niece. And my sis txt that he sould not be doing. He had been texting a woman from his work and she been sending him pic of her p***y 😡😡i just dont know what to do he hides his phone 📱 when in walk in to a room. I am about to leave his ass. A told his mum and she dose. Not believes me. HER son would never do anything like that. I need help please x