It isn’t my cup of tea to flirt with a guy whom I know at the very beginning as attached.  Though, being attached is not a requirement when you like a guy as a friend.  Or even you "like" him, yet you know it is not proper, then I do not see anything wrong with that.

It isn’t likewise my agenda to "get involved" with someone who is no longer available or to "grab" other girl’s boyfriend/husband/common-law-husband.  However, I do not deny having a relationship with someone attached before.

Right now, things changed.  I learned from my mistakes.

Nevertheless, that is not the main story to tell.

I care less and do not give so much effort to "argue" with someone who claims to be the gf/wife.  Am not the proper party to be questioned about any unsolved breakup or whatever you call it.  Ask your bf/husband.