<human>: He told me when we first started dating that they had broken up 4 months ago... Found out last night that is all a lie, they are still engaged, still together as a couple. I ended things with him as soon as I found out. My question is, how do I approach this with his Fiance? I do not know her at all, I do know her facebook though, should I just send her a message on there? I know that if I was her, I would want to know that my husband-to-be is going around fucking other people... Help please? Thank you in advance.

Can you succinctly summarize the text in 1-3 sentences?
<bot>: Just found out boyfriend of one month is also still engaged and cheating on her with me, how do I tell her this?