Episode 1.13 - what the heck? (SPOILERS)

I really started to like the show until the season 1 final but then...

Why heck did Peter LET her eat his face off? Instead of just killing her in human form? Or why not kill her with that nice ax while she is still tied up?

And why the heck does the sheriff suddenly show up? Who writes this *beep* It makes no sense at all! How did he know where they are? And why go there? It's just such a random act of story butchering!

He just starts shooting Shelly without any questions? IF he saw her kill Christina then he also saw that she was a *beep* wolf. If he DIDN'T saw her kill Christina then all he saw is her standing there! So why does he start shooting? Makes no sense.

Why doesn't anyone explain to him? And now Shelly is framed? This is so stupid :(

EDIT: Oh Jesus and I hadn't even finished watching the episode... it gets worse! How does any of this make any sense? Did they need to write out tons of characters out of the show because the actors had enough?