Life does, indeed, go on. That "new" wife no more replaces the dead one than having a new baby makes up for one who died- they are separate entities.
Nevertheless, at some point you realize you can't talk to an empty chair, the silence ( oh, God, the silence... ) becomes too much, and you go forth, and do... other things.
And if you're a little bit lucky, you find someone who likes you, too.