You mention grandkids...you must be of menopausal age then. Whether before, during or after, hormones can wreak havoc on your mental condition. IMO those horrible thoughts come from anxiety. It's normal to worry that a loved one will get hurt, sick, or worse. These tend to get worse when under stress or hormonal issues. And your concerns about yourself I think are also expressions of anxiety. I know when I had severe anxiety and panic attacks, I would have similar thoughts and was afraid I'd freak out for no apparent reason around other people. It never happened! Also, if you're like me you think too much. I don't know the cure for that.