When my Gran found my Porn collection

I'm Donald 23 single live with my Gran Mary 67 widow, I moved in with her on getting a job in her neighborhood 2 years ago. I come and go as I please and everything was okay. I have a some really hard core porn mags I use to masturbate while reading them. Then last December just after Christmas I came home and caught Mary Masturbating herself on my bed reading one of my porn mags. I was shocked and excited at the same time and got a hard cock and Mary on seeing my hard cock, asked me to fuck her. So I did and we have been fucking regularly since then.