I agree with shywon that you don't need to get into the middle of this. But if your best friend is just coming to you wanting to talk, I see nothing wrong with discussing this with her.
My take: if the ex-wife has already moved her new boyfriend in, why should she care if your best friend (or anyone) is getting involved with her ex-husband? (They are actually divorced, right?) Of course, this will most likely change the friendship between the ex-wife and your best friend. It could get awkward...but not necessarily. Your best friend will just have to decide whether it's worth risking a friendship in order to be with this man...if that is what develops. If they become involved, your best friend could eventually become the stepmother to these kids, could be complicated.
I know you have the best intentions trying to help your friend out, but the reality is that your two friends need to work this out.
I agree with shywon that you don't need to get into the middle of this. But if your best friend is just coming to you wanting to talk, I see nothing wrong with discussing this with her.
My take: if the ex-wife has already moved her new boyfriend in, why should she care if your best friend (or anyone) is getting involved with her ex-husband? (They are actually divorced, right?) Of course, this will most likely change the friendship between the ex-wife and your best friend. It could get awkward...but not necessarily. Your best friend will just have to decide whether it's worth risking a friendship in order to be with this man...if that is what develops. If they become involved, your best friend could eventually become the stepmother to these kids, could be complicated.