<human>: Can you provide a brief rundown of the text in within 3 sentences?

I've had a friends with benefits arrangement with my housemate Scott for a quite while now, a few months ago I ended up hooking up with his good friend Mark at a party and we've been unofficially seeing each other since.

A couple of weeks ago Scott got himself a girlfriend and called off our FWB arrangement, but he also told her about us and the situation with Mark and she is really unhappy about it. 

She is trying to convince Scott that he needs to tell Mark about us having been FWB and saying that he has a right to know.

Whilst Mark and I are not official yet, things are getting pretty serious, but do I really need to tell Mark that I've been sleeping with my housemate/his friend up until recently? 

If so, how do I even bring it up?
<bot>: I'm FWB with my housemate, and now dating my housemates friend, do I need to tell my new bf that I've been hooking up with his friend for months?