I have been dating this man for a year... nothing seemed off.. yesterday a friend told me he has a girlfriend already .. they been dating for 3 years... I feel terrible.. firstly because I feel like a side chick now... and secondly how could I not realise .. I was so blind in love....what should I

Do? I still feel maybe he’s not dating anyone else .. how to be sure of this.... if I confront him obviously he’l deny...