I don’t know why I get like this

I don’t know why I get so petty like this….

On Christmas, I went through my boyfriend’s phone. (he gave me permission ) I was going to the messages to look at something his niece sent him he told me to look at but while getting to it I saw “smoke one friend” to this number so I typed it in and saved it to my phone. But he sent that to that “friend” that Monday of Christmas week. My boyfriend and I have had conversations about him smoking weed and how he would stop smoking after Christmas because that’s one of his goals for the new year. So My boyfriend recently stopped smoking after Christmas. Earlier today, I called the number private to see if it was a male or female and it was a female. I’m a bit irritated because we talked about having friends of the opposite sex and i also asked him did he talk to other women and he told me no so I’m confused as to why he texting a woman wanting to smoke. I’m wondering should I confront him on it or let it go since it’s days later although it’s bothering me cause he lied and I’m not sure if he still talking to this “friend” and he is not smoking anymore or just say something and get it over with. I don’t know I feel so silly about this but it is also bothering me .