he said she was chasing him she said they were gf and bf
so tell me this what exactly does this girl have to gain by telling you anything at all
what motives could she have to contact you about anything
you know your h does he lie or does he tell the truth did he at the time complain about this girl chasing him or was it something you found out later
look for the evidence think back to what happened around the time
don't just believe someone without considering the reason behind them telling you (who they don't know) something
if she was so caring and considerate of your feelings she would not have chased him - or even allowed herself to be chased which ever the case may be - with a married man seperated or not
so what does she have to gain from telling you this