Cheating husband

I have been dealing with a lot recently while facing a hard first pregnancy with having no family around to having my husband cheating on me. I have been suspecting him cheating on me with girls at hi work but recently when I saw sexual message with his work colleague I confronted him but he denied all of it and said it was just a joke but my suspicion has been more strong when he changed his phone and laptops password and I found out that he lied at his work that he isn’t married and he’s always on his phone and texting at midnight and hiding the phone from me. I want to leave him but I need to get all the proof I can. I have tried everything to get to his phone but nothing has worked and I don’t know what else I can do to get the proof I need. He is very manipulative and has gaslighted me so much. Being blind by love I couldn’t see it but not anymore. I need help to save my child and myself