Hiccup's mother from "How To Train Your Dragon 2"

This sequel came out a little while ago, and next to a fairly bland plot, it introduced us to Hiccup's mother. I didn't know anyone cared, but they included her anyway.

The reason for this woman's absence was unmentioned in the original movie, but everyone assumed her to be dead, and this movie reveals that they believed dragons had killed her.
It's a very crucial bit of information that would've explained Hiccup's father's reluctance to listen to his son and befriend the dragons in the first movie, but since they said nothing about the mother's cause of death then, I can only assume the writers just now came up with the idea to link Hiccup's mother to the creatures.

So, what is this woman's backstory? It appeared that she was such a people-hating hippy, she decided to ditch her own baby and husband to live with the dragons who abducted her. Brilliant. 

The fairly collected reaction from Hiccup upon meeting her and the lack of "WHY DID YOU LEAVE ME, WHY?! HOW COULD YOU LEAVE A BABY BEHIND! SHIT, MOM, YOU'RE MESSED UP!" in the conversations with her made me..quite furious, actually. I was happy the movie paused after that scene, as I needed the time to digest this bull.

The movie tries to portray this woman as some kind of awesome warrior and dragon trainer who did what she had to do, and deserves her son's forgiveness for "perhaps slightly overreacting", but I find her a terrible woman who only cares about herself. She just uses the excuse that she felt Hiccup was saver without her to make her appear less of a selfish bitch.
But her excuse simply made no sense, as she already discovered dragons were peaceful creatures, since she is living with the damn beasts since day 1. How would Hiccup be saver without her? She's always been right about the dragons, and she knew that. The dragons wouldn't kill Hiccup, so what's the danger she wanted to keep him from?
I just hate this character so much. She even dares to hestitate about returning to her husband and child, even after knowing the whole village accepts dragons. Just what is this woman's deal? 

The way she acts and the way she talks to Hiccup makes me think she is mentally crippled and socially awkward. Who chooses a bunch of flying lizards over their own flesh and blood? No good and mentally sane mother thinks her absence is best for her family, they consider themselves best for their family.
She is a shitty addition to the movie. I'd rather have her dead, if this was the story and character they'd be going for.
When her husband dies, you see everyone crying, but her face is the dryest of all.

Every time I see this woman, I feel so angry.