Am I being a bitch?

My bf and I are in a long distance relationship for the past 7 months, although been together for 3 years now. So the situation is this- I found some old texts between him and his best friend, where they were addressing each other as hubby and wifey, & at some point she mentions she wants to have sex with him and he flirts back replying he is working on his body so he can look good for her. Now this was a long time ago, a little more than 1 year into his relationship with me. I confronted him about this recently when i found out (I may have called her names, i was very upset) but, he said she is not important to him. I know it was a long time ago and should just let it go. But he also mentioned she flirted with him back when he was single & she was dating his other best friend. So u can guess why i don't like her at all.

But the other day I found out that he sent her a birthday gift to her new address. She received the gift on her birthday but didn't even thank him. What upsets me more is he just got a job & that's his 1st job. He said she is not important but I feel bad that he didn't tell me about it. & I know I'm being petty but i thought after his family i should be the one who gets a gift from his 1st salary then comes all these other girls turn.

Anyway, he usually doesn't remember anyone's birthday. But he remembered hers and even sent her a gift. I love him but this best friend of his bothers me a lot, like no other female friend of his ever has. Idk how to make him understand that i don't feel good about this without sounding like a bitch while also keeping it short.

Also am i overreacting? I feel like my response to seeing those texts was normal but then i feel guilty bringing it up since it was a long time ago. Idk anymore if i should be angry, upset or guilty.

Sorry about the long post.