<human>: Give me a shortened version of the text

A friend [F24] of mine [M29] recently moved over 800 miles west to be with her LDR boyfriend of at least 3 years. Before she left I happen to know she slept with a mutual friend of ours at least once (possibly multiple times) in a blatant and shameless way. I've only met the bf once, and don't really know him at all, but I can't shake the feeling he deserves to know that his gf has been lying and disloyal before she settles in and potentially causes more damage.

Conversely, I also feel like it's none of my business and should stay out of their affairs (pun intended). Please help me figure this out!
<bot>: Female friend cheated on her LDR bf. He doesn't know, and I feel conflicted about spilling the beans.