I can’t get over the hurt I am feeling over what my boyfriend did, what can I do to let it go?

hey guys,
my boyfriend met two girls last year in October when him and a group of his friends went out to eat. they followed each other on instagram and started sending each other memes. i noticed he was following her and i asked if he knew who she was and he told me no. a few weeks later i looked at her stories and there’s a picture of her, her cousin and yes you guessed it, my boyfriend as well. i tried my hardest to calm down so i waited a few days before talking to him. i finally answered when he called and i asked why he lied and he said he was sorry at the time he didn’t think it was a big deal and he is truly sorry. it was the fact that he lied to me about it and didn’t think i was going to find out. ngl, i am kinda iffy about guys in relationships having female friends and vise versa. one of them always ends up catching feelings. i know girls ends up falling for the guy in relationships so i don’t like it. but anyway, they don’t talk anymore according to him. i do check his instagram and he doesn’t. i want to forget about what he did and be happy, but i honestly don’t know how. whenever i see him i immediately get sad, angry and disappointed and i don’t want to feel that way anymore. how can i let go of the hurt and anger.
Updates
1 y
oh okay. in your opinion what is a reason he would want to be friends with the opposite gender?
I can’t get over the hurt I am feeling over what my boyfriend did, what can I do to let it go?
Post Opinion