your step-dad isn't appreciative of your grandmother or what she has done for him. He just wants to use her as his scapegoat when things don't go well in his life.
He needs to get a grip on his own life.
I hope he backs off your grandma and looks hard into the mirror at himself. I really love those surreal moments. Buy him a small mirror and tell him he really needs to take a good look at himself.
oh, well I don't wonder why, but I'm sorry about that.
Sounds like a narcissist, they blame everyone else for their own faults. They also like to hurt people.
Well, a person never knows what is in the past, but personally I believe there is a time one should stop blaming others for your life. Just make sure that you always treat her with respect. Keep well.
Maybe ask your Mom. We would have no idea why.