<human>: I [M21] recently started dating a girl I'm really interested in and she is really genuine and also really into me, I think we're going to go far. But I also recently started having sex with a friend whom I've had for almost a year, we're really close **as friends only** and find each other attractive but I don't really want to 'date' her. My FWB [F20] knows I'm dating this other girl [F21] (who I'm not serious about, but expect it to become serious, we met a month ago), but the girl doesn't know I have a FWB (this happened quite recently).
I haven't slept with the new girl yet (we're taking our time), but I've slept with my FWB starting a few months before I met the new girl. I'm planning on stopping the FWB thing once I first have sex with the new girl..

Can you provide a brief overview of the text?
<bot>: When should I, if ever, tell the girl I'm dating that I have slept with my friend? in a point where we're not serious.