Found something while snooping . . . and now idk what to do

Im going to try to make this as short as possible, so please bare with me 😭

So my boyfriend and I both know each others phone passwords but we dont really touch each others phones, so I'd like to think that there's a high level of trust between us. However, one night I just casually went to his IG and saw that he was messaging a girl. A girl (lets call her Alexa) that I've actually known for a long time. I know that before my boyfriend and I got together, they had a slight interest in each other, but then he met me and she got pregnant, so I guess they just went their own way.

In the messages he basically is just telling her that she very talented and that he likes her work. He's also said that if she needs somebody to talk to that he's there for her. The problem is that these messages dont really strike me as cheating or having any intention to do so, maybe he's just being a genuine caring friend?

But the other messages that do slightly bother me are stuff like "when are we hanging out" (twice) "horrible stuff happen to you but you still have a beautiful soul" . . . so idk what to think.

Since we both know Alexa he would always tell me how she's really annoying on IG and snap because shes always posting singing videos but nowwwww he tells me that she is really talented and even plays her songs in the car sometimes.

He has talked to girls in the past (it was two times and both times the girls reached out to me). This was in the beginning of the relationship which was like 3-4 years ago. I think he's changed a lot and he regained my trust, but in the back of my head I can't help but think that he might do it again and actually cheat this time.

So my dilemma is what to do next . . .

1) Confront him and tell him what I found?

2) Snoop again and see what else I find; do some detective work?

3) Just try to forget what happened and see if anything comes to light on its own?

PS. Alexa knows we've been dating for 4 years and I wanna say that she's a genuine and caring human being, I dont think she'd be down to be a side chick.

Helllllppppppp.