AIW for feeling uncomfortable with my boyfriend’s friendship with his coworker?

I (27F) have recently started feeling quite uncomfortable with my boyfriend’s friendship with his coworker (23F). My boyfriend and I have a great relationship, he’s typically very respectful of my boundaries and we communicate very well when we encounter issues, however a few issues have popped up related to his coworker.

For added context, my boyfriend often goes out and drinks with his team, sometimes with clients and sometimes just as a team. I have met this coworker a few times and found her to be lovely and we got along well. He has never referred to this coworker as a friend of his previously, he doesn’t really interact with her when I’ve been around them both and often only has negative things to say about her, but since we have had issues, he now says she is “one of his close friends” and it’s all making me feel quite uncomfortable.

This began about a month ago when I found a video in his phone of her at their work Christmas party that someone else took/posted but he had screen recorded and saved it to his phone. I expressed that I found this a little bit bizarre and it made me feel a bit weird and he dismissed it by saying it’s just a funny video and someone else told him to save it. I still felt a bit off but I took it at face value and moved on. Since then, it has come out that this same coworker recently cheated on her boyfriend with another male at their work who also has a partner, obviously this wasn’t with my boyfriend so I didn’t have an issue with him about this but in all honesty, it did make me feel a little bit more uneasy as I now know she is capable of crossing that line with a coworker.

I then found another video in his phone taken at a team night at a pub, this time he recorded it on Snapchat and even though the entire team was at the table with them, he recorded only her, posing with her drinks and then once again, saved the video to his camera roll. I once again expressed that this made me feel uncomfortable as it felt like he was focusing on this one girl in a group setting and having these videos saved to his phone just feels really odd. He told me I’m making an issue out of nothing, that she’s just a really close friend and that I’m clearly just threatened by this specific girl, which made me feel even worse and led to quite a big argument as I felt my feelings were being invalidated.

The next day, I was working from home and he has called in sick. I still feeling a bit off after our fight and had a gut feeling to go through his phone and I found that he had deleted a text from this same coworker. The text was quite innocent in nature, her saying that she hopes everything ok and that she’s always there for him and there to talk if he needs, a text I wouldn’t think too much of but the fact he deleted it made me feel quite suspicious, I brought this up with him again and he said that he deleted it because he didn’t want me to get annoyed at him over it after our fight last night, I explained that him hiding it from me is what’s making me upset and he’s denying that he hid it and said his intention was to “not upset me”.

In my last relationship my ex would often hide things from me and lie which gave me awful trust issues, I’ve worked extremely hard to overcome these so I didn’t wrongly transfer these issues from my past onto my new partner but I do feel them bubbling back up and I could really use some outside input.

Am I wrong for now feeling uncomfortable about this friendship and just projecting past trust issues onto a situation that could be perfectly innocent, or is this valid?