Kramer Vs Kramer-Peter Downie

In the movie Kramer Vs. Kramer, Joanna, Billy's mother is granted custody of Billy over his loving father Ted Kramer.  I believe that Ted should have been rewarded custody of Billy because he was responsible, unlike Joanna.      Ted was a very responsible man and father in the movie.  He supported Billy by working hard but still managed to fit all of Billy's needs.  He also knew how to discipline Billy, like when Billy threw a temper tantrum over his dessert he put him in his room and didn't let Billy get away with his childish actions.  You could tell Ted really cared about winning custody because the second he lost his job he worked to get a new one so he could keep custody of Billy.  Joanna left Billy and Ted in the middle of the night, she was extremly un-happy so I understand why she would leave but to come back and make Billy have to change lifetyles for the third time is very irresponsible, also you never know when she is going to go haywire again and leave Billy at Ted's front door.  That's why Joanna can't be trusted with raising Billy.