I need help with trusting again.

When I was 2 months pregnant, I found nude pictures and dirty messages on my boyfriends phone to and from all sorts of women...there was a lot of them. I confronted him about it and he said he had a problem so he started going to counseling. Our son is now almost 5 months old and I have not seen or heard anything to make me believe he is doing that again but I still have trouble trusting him. He got a mew job which is a great paying job but he has to travel and it’s just been really hard for me to relax while he’s away. Any advice? How do I start trusting him again?