"A mother, suffering from depression drowns her children because she fears they are posessed."  I believe that maybe she was on drugs or had some mental issues, if she got help from people and got put into a mental hospital and became better, then i believe yes, she should be forgiven, but only if she realized what she had done was bad.
     But then I also believe that even if you are depressed you can take medication to help and ficx the depression. Just because you or someone is depressed does not mean they should do something crazy like that. She could have gotten help and her kids could have been put somewhere else for awhile until their mother was better and had control of herself.