Background
My boyfriend and I are in our mid-20s and have been together for a little over two years. In the beginning, we had a lot of arguments over small things because we didn't know how to comfort each other or understand why certain things about each other bothered us so much. These arguments were frustrating and often dragged on for hours with us both trying to prove our points. Things got really bad around the 1.5-year mark, with near-daily arguments making both of us fed up.
My boyfriend is generally really anxious and has abandonment issues but I and everyone I introduced him to all got the impression he's super caring and cares a lot about me. He's never taken advantage of me in most ways, never belittled me about anything, never used me for money even though he doesn't make a lot of his own money, etc. He's truly went above and beyond in planning things for me and trying to make me happy even when things were rough.
The Incident
One day, while I was using his phone, he got a text from some girl, asked for her phone back, deleted all his texts, and wouldn't let me see his phone. He said it was a girl he had hooked up with before we started dating, who he'd stayed in contact with but almost stopped talking to after we got together. Recently, he helped her with job applications because she became homeless. Although she lives across the country and I wasn't worried about physical cheating, he admitted she had flirted with him occasionally, but he "ignored it". He deleted the texts because of our constant arguments, and not wanting to give us a reason to have yet another one.
Instead of moving on, I became paranoid, constantly checking his phone and asking for proof of his whereabouts. I eventually got therapy to address my issues and stopped snooping for a month, which improved our relationship tremendously. However, I later asked him for proof of where she was, and he reluctantly complied.
Another Incident
He got a text from a female friend asking to hang out. I checked his phone and saw they had been calling each other 3-5 times a day for brief "check-ins." Weirdly, these calls were usually only 1-2 minutes in length. After the previously mentioned incident where I became really suspicious of him, he got worried we'd fall into arguing again and deleted all their phone logs. He also said after that happened, they briefly got coffee, but he hadn't seen her for years prior to that. She's also called him asking to hang out with her and their mutual friend before all of this, I heard the conversation and it seemed completely innocent.
Current Situation
Now, I'm confused. Therapy and self-reflection have helped us stop arguing completely, but I'm still suspicious of his commitment. The coffee meeting could have been cheating, this is dumb to say but the girl is less attractive than me, and their recent conversations seem normal. Our relationship is otherwise strong, and he is traditional and family-oriented, wanting marriage and kids. He spends almost all his free time with me, as he has few friends(not guessing, he genuinely just has pretty much no friends which I know is a little ironic considering he's hidden interactions from me but it's true)
How do I move on from this and believe him? Should I? After the first incident, he got easily upset when I asked for proof of his whereabouts and that our I'd become so distrusting of him. Now, he's open and understanding whenever I get concerned and handles it well. He's currently on vacation with his family in a foreign country and sends me video updates of everything he's doing and I can video call him whenever I want.
This whole situation is extremely difficult to wrap my mind around, I know in just about every similar scenario it would seem like cheating. And reading it back it almost certainly seems like it. But I wish I could get across by text the regret I feel from him and all the genuine good she's done for me over the years. His anxiety has led him to acting poorly towards myself and his family, and I don't know if this is trying to cope but cheating is the last thing I would've ever expected of him. He cries every time kids come up in movies or in discussions because we started having that conversation pretty deeply around the time the second incident happened. I'm lost and I'd appreciate any input.