Update on the situation... I have decided NOT to do it. My family can go to HELL.
If I do this then know for a fact that I'll just wind up screwing myself in the end - again, while the two parties (my deadbeat sister & BIL) who SHOULD be taking responsibility for this get off scott-free.
Even if it means that I contact child services to rectify the situation. I will do what I must. I am SICK of sacrificing ME on account of "family" that screws me over again and again.
Call me selfish, call me evil, but this is what I have to do. I can barely take care of myself - what business do I have raising kids? Especially kids that aren't mine???
I can't do this. I just wouldn't respect myself. And truth be told, I don't even like kids. And let's be honest - do you REALLY think that I have the mental capability of being responsible for another human being?
I know that many of you would do differently if you were in my shoes, but I guess that you're a lot stronger than I am. It takes a LOT of strength to put out enough forgiveness and love in order to take on such a burden. I guess that I am just too angry a person, and frankly I have NOT known enough forgiveness and love in my own life in order to pass it on.
I have to do what's best for me. I cannot take this child. I'll just wind up abusing her.