HolyKnight

Shor answer: She got pregnant and want me to take care of the dumb ass child of her and lost my girlfriend because of that.

So she wants you to raise another man's child even though it was conceived after you two were Fin and you had no hand in it's creation? Well I can understand your anger, but it doesn't honestly justify killing the woman. It's unfortunate that her...demands resulted in you and your girlfriend breaking up, acting on violent impulses of vengeance tends to cause nothing but regret later on

You're probably gonna hate this advice, so I'm honestly sorry in advance, but the only thing I can tell you is to stay away from her and keep citing the fact that if the kid isn't yours, you have no obligation, either moral or legal, to care for it.