Going to beat a bitch

So one day I was going through my boyfriends phone for the hell of it, I trust him and everything we just exchange phones like once a week like if wants to see mine I see his and if I see his, he sees mine. I finished the pictures (I just love to look at the stuff he takes) but then I saw on messagerr he sent a picture to an old friend of his and she said thank you. So I was curious so I went trough it and she was asking him for a love letter he declined her on it and said "what about a post card instead" so he sent her a selfie and then she said thank you with a smile face. This was all in December 19th but I haven't been able to stop thinking about it I saw it like a week ago or so. I've met her she seemed pretty cool and now I just want to shove her face into the concrete. I hope she wasn't leaded on because I know some girls are that desperate. What do you guys thing. He's a great guy and I love him just I know in the past he wasn't happy and this girl he was crazy about he sexted her and he told me straight up when he met me, and I chose to look past it and it seemed nothing like that even the girl who told me about he let me read through them not pictures or anything though and he hasn't talked to her since. That's when the phone thing started because we've both been cheated on in every relationship.