I was living in Alaska at the time, newlywed of about 2 years.  I was in my mid-twenties and horny all the time.  (and hard)  I never thought Betty (mom-in-law) was hot at first.  She was in her mid forties and overweight.  My father-in-law, D, loved to hunt and was gone a lot.  I knew he wasn't really interested in sex with his wife (he told me) and I think he was having an affair.  I loved my wife, but she never wanted as much sex as I did.  (I could have had sex at least 3 times a day to be satisfied)  Anyway, that's the setup.

It was in the middle of the winter and D was out hunting.  Betty called me and needed some snow shoveled. So, I went over to her house and did the chore.  Afterward, she had a nice hot coffee for me laced with Bailey's Irish Creme.  It was dark (winter was always dark) and Betty was in her thick robe.  (nothing new, I had seen her in it many times like this)  We were talking and drinking and I was really having a good time.  She dropped her napkin on the floor while telling me something and when she bent over to get it, I could see her big tits.  (she was nude under her robe)  D had told me she was horny all the time (unlike her daughter) and that she was always pestering him for sex.  I made sure to get a good look at her tits and she seemed to be taking her time.  When she sat back up, my face was red and I was getting hard.  She never said anything, but I knew she saw me and she smiled and asked if I would like another drink.  I said yes.  This time it was something different (straight Captain Morgans I think) and it was a big glass.  We talked some more and I was really buzzed.  She said she was going to call my wife (her daughter) and tell her I had too much Bailey's and would just spend the night on her sofa.  That was fine by me, since I was in no shape to drive.  After the call, she turned the lights down and I thought she was going to bed.  But, she walked back and leaned over to give me a kiss goodnight.  I thought she would kiss my forehead and I would be able to see her tits again.  Instead, she gave me a soft kiss on the lips and lingered.  Her lips were full and warm and she was a good kisser, so I kissed her back.  (probably the alcohol)  Before I could stop myself I was in a full blown make-out session and pulled her down on top of me.  She opened her robe and I started stripping, then I fucked her brains out.  She was great in the sack!  Way better than her daughter and her plump form felt really good riding me, not to mention her huge tits in my face.  

When I finished, cumming inside her, she continued to lay on top of me, kissing me and telling me how good I was and how big I felt inside her.  She kept on moving her soft wet pussy around on my cock and kissing me and soon I was hard again and pumping her sweet pussy.  I had totally lost track of what I was doing and who I was doing it with.  After I came insider her the second time, I was exhausted and she took my hand and led me to her bed.  I slept really well that night and was surprised to find her dressed and making breakfast in the morning.  I felt bad for cheating on my wife with her mother, but that wasn't the end.   (I've been really lucky...)

More later...