Contact with ex

So I recently found out that my SO was in contact with his ex. They not only were talking, but talking about him leaving me to go back to her. These messages were from April of this year and stopped only a week before we got our BFP!  As far as I had known we were happy and ttc. I had been feeling a distance in him but I assumed it was just work stressing him out. The last few months have been great. We have been making plans for baby and enjoying our marriage. 
I found the messages in his email when I was looking for info on in his email on a job he had heared about. The emails were hidden in a folder along with our tax information. The conversation ended abruptly about a week before our BFP and there was no sign of it restarting. 
When I found these emails- I freaked. He said he was very wrong for what he did and that he is sorry it happened at all. He says the conversation ended the way it did because he realized how foolish he was being and that of he had really wanted to be with her he would have stayed in the first place. 
I have decided to forgive him but he is aware he currently does not have my trust and it is his job to show me I can one day trust him again. Marriage is a bid deal to me and I don't believe  in throwing something away over bad judgment. We haven't been married long- almost a year- but to me we made a commitment that has impacted our life and I don't see divorce as an option right now. I want us to be happy. 
The biggest part of all of it that bothers me is that he let her trash talk me throughout the entire convo. I find I am having a hard time with that aspect because to me it shows his lack of respect for me. Has anyone else gone through this and how did you work it out? It seems we have just gone back to normal life (he most likely wants to pretend it didn't happen) but I am still hurting over it. I'm just looking for some encouraging words to help ease the pain. Thank all you ladies in advance- I know these are touchy subjects. Thank you