Cry-Baby (1990)

A Drama & Thriller In One!
A woman is reunited with her biological mother after she was taken by child-protective services when she was little. Her mother was suffering from postpartum psychosis and supposedly put her into a bathtub of scalding hot water. After all these years, her mother is still psycho. She meets her daughter's lifelong foster parents, husband, son and new-born baby. As she tries to bond with her daughter, extreme rage and jealousy builds up inside of her towards the foster parents. And when her anti-psychotic medication runs out, she goes on a violent and sociopathic rampage against the family. It gets to the point where she plans on completly destroying every person in her daughter's life so they can start over, just the two of them. Her daughter realizes what she's up to when the bitch tries to kill the baby. The same way she did before, a bathtub full of steaming, scalding water. It turns into a shocking, heartpounding turmoil between the mother and daughter which leads to emotional pain, violence, and certain death.

A very good movie
The story line for the movie is very good and convincing and the acting by every character was believable and sincere.