What is normal behavior in a marriage?

My husband and I have been married 5 years and 3 times he has gotten a coworkers number to flirt. Nothing seems that it has been more than the flirting via texting. But this last time I feel like I m really done. I was 40 weeks pregnant when he last flirted with a girl. He is set on not moving out. We both split the bills in everything 1/2 ways. I primarily care for our 2 girls 2 and 5 months. So it’s not as easy for me to just leave?

How can men change what actions need to be done?

How do you make it work living together.

I don’t feel like I could trust him again even though I really wanted stay with him