I was about 5 or 6 when I saw it, so mid 1990’s.
It was in English.
It was on TV, but it was movie length.
It was in color.
I know it was made sometime in the 80s or 90s cause it’s not super old. I know it’s not Rosemary’s Baby. All I can remember is that a man and a woman had a baby and it was really hard on the mom especially cause the baby was constantly crying and nothing the parents did would make the baby happy. Until one day they had to hurt and kill someone I think in self defense and the baby happened to be a witness and it started laughing and such. The parents piece two and two together after the baby goes back to crying and they end up having to hurt someone again. So they basically kill a few people and then one of the parents tries to back out and the other one kills them and after that parent gets killed, the baby stays happy. Then the surviving parent goes on a train with the baby and goes and starts their new life together.
I’ve been trying to find the name of this movie for years and I’m starting to think it was just a fever dream.