I know this does not help much right now but you and your family are doing the best thing for Thunder and for yourselves. You are right about life going on and he is clearly telling all of you to let him go, the time has come.
Hugs and prayers for all of you that you have the peace,strength and love to get through this. You have all of us here at PT as well. That was one of the main things that got me through both passing of my precious babies was all the wonderful, caring, loving people here on PT that understood and knew exactly what I was going through. You can have us hold you up for a while.
You can pm me anytime also, I know we don't know each other but I will always listen.