How do I stop Catastrophizing?

My daughter lives with me and is 5 months pregnant and recently found out her son is missing a bone in his right forearm. They don’t know the cause and she’s having genetic testing. She also found out she has what’s called a 2 vessel umbilical cord which can cause several physical problems for the baby. All I keep thinking about is how this is not what I want for my future grandson, my daughter or myself. I just keep thinking about how horrible our lives are going to be. So I want to change my thoughts about this situation but don’t know where to start