Need your advice!!

Hey everyone, please read fully before commenting. And please be kind, you can be honest and kind at the same time. I just need a little help processing this and figuring out what to do...

My boyfriend and I have been together for 8 months. Before we made it official, we talked about Tinder (because that's how we reconnected), and he told me that before we reconnected, he used it not just for sex or relationships but for friendships as well. He said there was a couple girls that they instantly decided to just be friends from the start. From the conversations we had, I never realized he was still friends with one of them and talked to her every other day. He talks about a few of his close friends every once in a while but never said specifically one of them was this girl. So anyway, about 2 months ago we were talking about Tinder again and we asked each other if we still talked to anyone from there as just friends. I said no because I recently had stopped talking to this one guy I kept in touch with as just friends (he knew about this guy previously). He said yes and then told me which of his friends it was. He asked if it made me uncomfortable and said he would stop talking to her if I wanted. I told him the only thing that made me uncomfortable was that he never told me it was her specifically before. It had always sounded like he wasn't still in touch with this tinder girl since we started talking. But I also said I would never tell him who he could or couldn't talk to because I trusted him. I told him the decision was 100% up to him and I would respect whichever he chose. He told me he would just stop talking to her because he wanted me to be comfortable and secure. So I let him know that if he decided to do that, I needed him to be set in his decision. If he wanted to keep being her friend, that was fine with me. But if he decided not to, he couldn't just change his mind and be her friend again or else it'd be breaking a boundary we were creating. He agreed.

Now, the reason why I said this (and he knows this as well) is because I was in a 9 year relationship that ended really badly and in the beginning of that relationship there were issues with him and my best friend talking behind my back, him saying he would stop talking to her altogether, but then he restarted talking to her and didn't tell me until a while after. Clearly, that caused a lot of trust issues. Hence, why I need help figuring out if what I'm about to say is as big of a deal as I feel, or if I'm overthinking it/over reacting..

So here it goes: a couple of days ago I walked past his phone and it vibrated. He asked who it was and I said "idk someone on snap" so he went over and looked at it and said "oh it's that girl I stopped talking to. Idk why she keeps texting me". I tried to not let it bother me, but it did. So I told him it was bothering me and he said I could look through his phone. For hours I told him that's not what I wanted to do because I wanted to trust him and I didn't want him being disappointed or upset with me. He promised it was okay so I asked just to see the snaps with her. That's all I needed for clarity. He showed me, but it's snap, so of course the only messages were from that day. It was just like 3 small things, nothing of bad nature. However, there were a bunch of voice messages from before he supposedly stopped talking to her. He let me listen to a few and I told him I didn't need to hear anymore. There was nothing bad on them, but I still couldn't help but feel unsettled with the situation since he had replied to her that day. I told him this and he told me she made a story (I'm assuming on snap) saying she was suicidal. He said he reached out to her a couple days earlier just to make sure she was okay. But the very short conversation I saw today was nothing about that. And I couldn't see the couple days previous because it's snap and they automatically deleted. He blocked her after that even though I didn't tell him to. So now I'm stuck here not knowing if he broke a boundary I set for a good reason and didn't plan to keep talking to her, or if he made that up and he just did it because he wanted to talk to her again. I also have no way of confirming if he really stopped talking to her at all. I'm at a loss here. I know that most people could easily get over this because there's no cheating, at least not that I can see. And he's never given me reasons before to think he would cheat. But my 9 year relationship was me ignoring red flags and forgiving someone that constantly broke my boundaries. I don't want a repeat of this. It hurts so bad thinking it could happen again. I want to trust him, but it feels like he betrayed my trust in a way. We haven't really had any issues prior to this with the exception that he won't change his relationship status on Facebook to in a relationship. His reasoning is that he's never been in a relationship before and he doesn't want to do this before moving in together as he's afraid it won't work out and he wants to keep his life private. We got over this issue as the plan is once we move in, he will change it.

Can someone please help and tell me if I'm seeing things clearly or not based on what I've shared... He's always been the most patient, understanding, calm, and respectful person. But I've done a really good job working on myself and not letting my past sabotage my current relationship. But now here I am confused if this is something big enough to walk away from or if I should trust him and move forward together hoping I don't regret it and get hurt in the future.