Review of Don't Knock Twice

Like I don't understand the ending? Yes! I am slow when it comes to getting movie endings. But like who really took the children? and why would the lady kill the Jess's husband and trick her into taking her place as the demon's slave?!? And do you think jess will kill herself or trick someone else into taking her place? Will there be a sequel? I just want someone to explain to me what really happened! So if anyone Would be sooo kind and do that for me I'll appreciate it. Thanks in advance! And I could kinda tell something was up with the lady from the beginning did anyone else suspected her too? And Was Mary evil? How did she become a slave? And Why was the witch messing with the mother in her dream?