Penny,
I understand your feelings quite well. My advice to you would be for you to call the girlfriend, since you are still close, and explain to her that it would be very painful for you to attend this shower. Maybe tell her that you could visit her when her and the baby come home? Just do something that will not bring so much pain stabbing thru your heart. It will be so very hard for you to sit thru that shower and think about all the "what if's." She will understand because she knows how much you love and miss your son. I've been there.....it hurts something awful.....go to the zoo....if that was your first thought, then go there....could it be possible since that was your first thought that Sean would want you to be there close to him? My heart goes out to you as you struggle with this. I can only tell you what worked for me and that was to not attend the party, to go be close to my son instead. Now I can see the girlfriend and talk with her and hold the child and all that. There is not so much pain associated with the child, although everytime I see her and the child, I still think of all the "what if's." I don't think that will ever go away.