<human>: Condense the text into a few key points

Throwaway Account. 

I met a guy at a place I used to work two years ago. I felt attracted to him but I was in a relationship at the time. Quit shortly after that and didn't have much contact with him. 

Found him on Facebook a few months back and sent him a request. He accepted of course at the time his Facebook said that he wasn't in a relationship. He messaged me two weeks ago.He confessed that he had always had a huge crush on me. I told him the feelings were mutual. 

We talked for a week before I lurked on his Facebook and saw some recent posts that a girl had tagged him in. Went to her page and it said she was engaged to him! 

I confronted him, but he said that had just broken up a few weeks ago and she must not have changed her relationship status yet. Me being gullible I believed him. He's told me everyday that he wants to see me and take me on the date of my dreams. Something didn't feel right about him so I checked her Facebook again today and there is no denying that they're together. 

On his page he appears single but on her page the evidence is clear. I always found out they're getting married in two months, and that she has two children that are very attached to him. 

I'm not sure if I should message her and inform her that her fiancé is attempting to cheat on her. Or ignore it because it's technically not my business.  

Personally if I were in her shoes I would want someone to tell me before I made a mistake and married a cheater. Who's to say he isn't doing this with more girls than me.
<bot>: Found out a guy that's been trying to go on a date with me is engaged. Not sure if I should message her before she marries him or ignore it.