Leave or stay?

I found out that my boyfriend I've been living with has been hiding a female friend from me dor months. His excuse was he thought i would get jealous and leave him. He has known her for a few years but did not start talking to her again till about 2 months after we started dating. He travels 3 weeks a month for work and he has been talking to her the whole time. He doesnt talk to her when he is home with me though, we have an understanding that I'm aware he watches porn when he is gone and goes to strip clubs with coworkers. And I've never been jealous before of that or his other female friends so I dont understand his excuse. They send sex memes back and forth, they are also friends on snapchat and instagram but I havent found her phone number in his phone yet. I'm currently 6 months pregnant and I dont know if the hormones are telling me to leave or if that's all me. But I do know there are things not adding up that he blames on being stupid. I found out about her after I went to use his phone to make a call, mine was dead and the code had been changed which was suspicious to me since we share our codes with each other. So I looked at his facebook messenger and there she was. So what would you ladies do, do I stay or leave???