Issues trusting my spouse to be, warranted or not?

Hi there, thanks for looking at this thread. It's a bit long, so bear with me, any insights you could give me would be super appreciated, I'm at a loss about how to handle this and move on. So a bit of back story for context. I'm currently engaged to my boyfriend of almost five years. I'm 26 and he's 23. He's my first serious relationship and the only person I've been intimate with. I have trust issues regarding him that stem from insecurities about myself, but also from some things he's done in the past during our relationship. I don't know whether I'm letting him off to easily regarding the things that he's done and forgiving him to easily, or if they are breakup worth offences. I don't have any girl friends to talk to about this sort of thing, which brings me here. The issues: 1: A few months into our relationship I caught him messaging a girl he went to high school with, telling her that he used to have a crush on her and if/when they're ever single at the same time in the future they should act on it and see what could happen. I confronted him about it and he said it was because I was planning on going to college abroad and that he wasn't sure if we had a future. It made us discuss our future and what we wanted from the relationship and I told him it wasn't okay, even if I was planning on leaving. I ended up not going to school abroad and we stayed together. 2: Two and a half years later we moved out of state, somewhere we had no friends or family. He left his email account open on my computer and I found emails sent to him regarding a Craigslist personals ad he had posted looking for casual sex. I confronted him about it and he said he'd been feeling really unattractive and felt unwanted by me sexually recently. He said he nothing ever came of it (he only got fake replies) and that he really just wanted someone to talk to, that he'd never actually have sex with someone. I would have broken up with him then, and I even told him that, but since I was 500 miles away from family and had no friends, I had literally no where to go. I told him as much and said if anything like this happened again it would be over. He cried and seemed genuinely sorry. We had a long talk about how he needs to communicate these things to me, as I can only fix something if I know it is an issue. Things were tense for a while but got better, in fact we'd been the happiest we'd been in a while. 3: Fast forward to a few weeks ago. I've been feeling a bit distant and insecure about our relationship. I go through periods of intense anxiety and depression. I was snooping through an old email account of his and found some old sent emails from about two months after the incident above happened. They were sent responding to Craigslist casual sex ads, including a semi-nude photo of himself. There were probably about 6-8 sent responding to different ads. I confronted him and he doesn't even remember sending them. It's just worrisome that what I thought was a great time in our relationship he was sending this stuff? Especially after he had promised not to do it again after the first craigslist incident. So what do you think? Should I have made a bigger deal out of it? Should I have broken up with him? I'm now having trouble trusting him at all. He's always been what I consider "flirty" with girls but what he just considers being friendly. He's a great father to our son and I love him very much, but I'm having trouble trusting him and having second thoughts about our upcoming marriage. I don't know whether I'm overly attached to him and our relationship since he's my first everything basically. Thanks so much if you made it this far, and thanks again for any insight you could give me.

I also think you deserve better ! Sounds like he is tempted or will in the end cheat on you. But it's a hard call when you have a kid together. But do you really want to live the rest of your life checking his emails looking for ways to discover his lies. Secret Life, If You really love him would You think about going to a couples therapy to have help finding out whats really going on with him ? You are both so young still. Might be a good idea to put the marrage off Till You Work out your issues. Its dangous What his doing answer adds like this on cragslist, who know What person is on the other side of the computer. I Hope You find a happiness ..... Thers are good men how there Good luck

There are some points in the post forum called NEWLY WEDDED just a couple days ago. I think that you might find some truths there that can help you.