Disappointed?

So i didn't get another letter today so far which kinda stinks. Those letters were making my day even though i wish i new who was sending them to me. :/
To me it's kind of ironic that when i mentioned his name the letters stopped coming but hey there's nothing i can do.
Anyways... can someone answer a few questions for me please...?
When someone remarries and knows the other person has kids and you marry them anyway, isn't that taking responsibility of the persons kids if they live in the household? And isn't it considered neglect when they look you out of the house with no where else to go? And truly should the stepparent have permission to discipline (smack around, spank, slap, ect.) the kids if they are not your own?
My stepmom apparently thinks that she can get away with smacking me and my siblings around. She also thinks that it's not called abuse or neglect to lock us out on the streets in the cold with no where else to go.
I have my sister Tamaira (13), my sister  Kimberly (6) and my brother Devin (8) to think about and care for. I've been their "mother" figure since they were born and i am not about to let them feel unsafe in a place where we know we're not welcome and don't feel safe in anymore. I have two other siblings in that house but they belong to both her and my dad. My dad says that "he disowning us if we can't do what we're told" but we were told that we can't come in the house unless my dads home. He doesn't get home tell 3am. It's getting cold out and i will not stand back and watch my siblings freeze and my family fall apart.