Is it normal not to be over the hurt he caused me?

My fiance and I have been together for 7 years. I have never been insecure about myself or a relationship. Toward the 2nd year of our relationship I found out he had been text messaging girls. He said they were friends of his and that was fine but he was hiding it from me and at first had lied to me about it. One of them he put in his phone as Nick when her name was nicole. He called her Honey,but nothing else indicating he was cheating. I stayed with him because I wanted to believe nothing happened b/w them. He deleted her out of his phone. Another incident would be him texting a girl from work he had known for 4 days.. And then again after that I found out he had been calling those MEET LOCAL SINGLES hotlines. He stopped. I stayed with him. These incidents were all in a 2 1/2 yr span, not all at once. And he did show me he loved me and told me often. This was 5 years ago. We now have kids together and sometime I look back on it thinking I was naive and stupid and that I should've left him. ....Is it normal for this to still affect my relationship with him?? Mostly a trust issue, even though its been so long since hes done things like this?