Is today the right day?

For the last 6 years ive been raising another mans child, he is called nathan, to be honest i cant stand nathan and only put up with the ginger haired little brat because i love his mum so much. Every fathers day i dread getting my card off nathan, his little monkey scrawl, claiming he loves me! makes me sick to my stomach! I think today is the day im gonna have to sit nathan down with my wife and my 3 year old wonderful daughter Gwen, and tell him the truth! im not his dad i dont love him and we may have to put him in care, i cant go through another fathers day like this help me please!