How do I get over this

So....this might be a little long. Sorry. I have been with my husband for a little over 2 years. Married for not quite a year. I have 3 kids that are from previous relationships. He is a great father to my kids. Does so much for them. He did not have any kids of his own. When I got with him, he was married to this other woman for 10 years. She was unable to have kids. They were just separating when we got together. We moved fast. He moved in right away. Seemed like he was the best man I could ever ask for. I had never had anyone treat me the way that he has. A year into our relationship I got pregnant with our amazing baby girl. That pregnancy was EXTREMELY hard on me. I was 35 and turned 36 when I had her. I had morning sickness for the first 20 weeks. Then it was so hard to move around because I have issues with my heart. He seemed so understanding and so sincere. Fast forward to 2 months after our daughter was born. I had this weird feeling that something was off. He didn't log out of Facebook one night when he went to get his haircut. Well he was talking to this other woman that he used to date venting to her about me. How I'm slacking on the housework, and blah blah. She was also venting back to him about her old man. I couldn't believe that he was talking to her behind my back. I stepped away from the computer for a minute because I couldn't believe that he was doing this...came back to reread them and they were gone. He was talking to her while he got his haircut and deleted the messages. Of course I freak out when he gets home. He tried denying it at first then admitted to talking to her for several months. He said he was so sorry and doesn't want to lose us, and it will never happen again. He did delete his Facebook but his job he is over the road for 12 hours a day. Sees many different people. That's how we met. Well I'm pregnant again...our baby girl is only 6 months old...and I feel like he is doing something again. I don't know if I'm being paranoid or what. How do I get over this? He didn't physically cheat but he would've I'm sure if I would have never found out..