Found my boyfriend talking to a girl off craigslist...

At the beginning of the relationship I found him on dating sites still but I was able to get past that. We have now been together almost a year and this. He said it didn't mean anything. He was bored and on there looking at trucks and he explored and got curious. 😡 It upsets me because I have never looked the other way. I want this relationship for the long haul and he said that scares the crap out of him. He hasn't had a serious relationship ever. How do I handle this?

We are both under a lot of stress due to loading jobs and financial set backs... I don't want to walk away from love.. but I'm so hurt and don't know if I can trust him again.