Is this “cheating”?

I have a guy best friend and my boyfriend knows it. But me and him sometimes talk about sexual things (usually stuff about me and my boyfriend, or him and his girlfriend). It’s more of like a conversation for us, we have no feelings for each other so it’s not like we’re trying to talk sexual to each other. I usually delete our messages if they involve anything sexual because I don’t know how my boyfriend will react. I honestly feel bad about this but again, it’s just a conversation. Would you consider this cheating? And is it bad that I’m technically hiding the messages so my boyfriend won’t see?

(Here’s an example of the things we say)