I'm so lost

Last summer before me and my boyfriend got together (3 or 4 days) before he has sex & got a girl pregnant we've been dating for a year now & anytime he mentions his child I feel the hurt all over again . Idk what to do or idk if I can honestly "get over it" ... I really need some advice or even just some encouraging words I'm a strong person with a good heart but I just don't kno how to put it behind me & forgive him