Rania78
Your advi e on these threads is always dubious. I have read a lot of your advice on these threads and one where you detailed your own history.
I went from thinking, "what an idiot" to understanding your perspective. That doesn't mean you are giving good advice though.
OP, just send a message. Worst case scenario he is still in a relationship and rejects you, which is the honorable thing to do on his side.
No, the worst thing that could happen would he that he lies to the OP, leads her to believe that he is single and cheats on his girlfriend with her, whilst lying to them both and not allowing either of them to make informed decisions about their own lives and demeaning herself in the process.
And before she knows it, the OP's self esteem is on the floor and she has wasted her best years on a man who she already knows has no integrity before it started.
The absolute best case scenario is that he leaves his girlfriend to be with her and maybe she is the perfect woman for him but, most likely, she would spend the duration of their relationship uncertain and mistrustful wondering who else he is messaging behind her back.
The best thing she could do is to move on, date, meet single men and maybe meet someone who is right for her.
As a pp said, that's not about being the moral police, its about self preservation and having bit of self respect. This isn't the only man on the planet and no woman has to chase every bloke they take a fancy to.