I need advice

I hang out with my boyfriend's best friend a lot Sven if my bf is not there. We talk about stupid stuff or eat dinner and all. Everyone I know keeps telling me that I'm being a horrible girlfriend and it's like cheating. I dont have any feelings for him and I find nothing wrong with it. Also I always tell my bf when I hang out with the friend and what we talk about or where we go. Am I in the wrong and shouldn't be friends with him or is it ok?