This was a book I'd found on my brother's shelf, and he's quite a bit older than me. We narrowed it down to probably being a book from the 70's or 80's. I'm really hoping someone here can tell me the name or author of this book, I've been searching for years.
I only remember a few scenes of this book, and countless Google searches using them have turned up nothing. So I'm turning here to see if I can possibly find the answers. The last time I read this book had to have been about seven or eight years ago.
The book starts with a man and a woman (who if I remember is his mistress) driving in a car. A large dog/wolf jumps out in front of the car or onto the hood (I can't recall exactly) and causes the car to veer off of the road. The scene ends with a wooden post ramming right through the mistress' head.
Another scene in the book involves the protagonist and his love interest trying to get to a house owned by a witch (or at least a woman who practices some form of witchcraft) who has turned a boy's brother (who she was sleeping with regularly but there was no real love she had for him) into the titular werewolf. But there's a traffic jam. In the scene it's also to be noted that the house has been set on fire.
This brother had a younger brother who had contempt for him, and the fact that he was with this woman, and he eventually turns into a werewolf himself, after being bitten by his brother or turned into one by the witch.
Still another scene is of a bag boy or whatever from a grocery store being attacked and killed by the werewolf in a phone booth, and he voids his bowels as he dies.
Another detail about it is that the witch who turned the boy's brother into a werewolf is eventually killed by the boy, and he keeps her body on a mattress in a cave somewhere, since he was in love with her.
A scene toward the end of the book involves a face off on a bridge by the protagonist and the boy, who I believe by this time is a werewolf himself.
It's very disjointed, but I've been looking for years on the internet to try and find this book myself, but have had no luck. So hopefully someone here and shed light on the title or author.