Wow, man! Who pissed in your cereal?
First off, she didn't treat YOU poorly. She treated the MC of the game poorly.
Although you play the MC, you and him are not one and the same.
Never forget that.
Second, Emily is not a whore, good sir!!!!
She has made some bad decisions in the past, but her actions/behaviors throughout the game show she is regretful of those decisions and actively works to keep her daughters from making the same mistakes.
Third, what the hell is a "MIFF?"
Is that a MILF that you're miffed at?
Like, what???
And fourth, of course Emily treats the MC poorly at the beginning of the game.
From her perspective, she has numerous reasons to dislike the MC such as:
1) At the game's start, the MC is little more than a lazy drunkard leeching off his father's (Marcus) patience and generosity.
2) Beginning the game, the Marcus and Emily are lovers. Emily is shown to be upset and unsatisfied with their current arrangement because Marcus has yet to ask for her hand in marriage. And it's insinuated/implied that one of Marcus' major reasons for procrastinating on marriage is due to the MC's presence and the MC's dependence on him.
3) Emily (rightfully) blames the MC for Markus' death. Although she doesn't know it completely, the MC's unwillingness to pay attention to his father leads to the MC missing the deer. That in turn causes the two to stay in the hunting grounds for far too long. And if you've played the entire beginning of the game, then you know the rest.
4) Emily seems to be aware of the attraction her daughter Mira has towards the MC and Emily doesn't want the MC to do to her daughter what her own first lover did to her - impregnate and abandon her. Something she knows (and we all know) a lowlife, lazy drunkard would probably do.
So yeah, from her perspective, the MC ain't such a great guy at the beginning of the game.