A few months ago, just for fun, my boyfriend, Jack, bought me a Sybian. Now I'm sure you all know what a Sybian is but for those of you who don't, I didn't, I'll explain.

A Sybian is a vibrating sex machine. It's in the shape of a box with a flat bottom and rounded top. On the top is a vibrating pad where you can attach variously sized dildos. The idea is to place it on the floor and kneel down straddling it and riding it like a horse. The vibrations are adjusted in intensity by a hand held remote.

When I tried it for the first time I thought I'd died and gone to heaven. I've never experienced anything quite like it. Jack, bless him, is not particularly well endowed in that department but this thing just filled me up and the vibrating pad fitted so snugly on my clit. When I switched it on I swear to god I had an almost instantaneous orgasm. It just blew me away and Jack too got really turned on watching me.

So all's well with our sex life? Well! not quite, you see I've become obsessed with the damn thing. I rush home from work to get in before Jack to ride it, I just can't get enough and it's affecting our sex together. I just can't cum with Jack no matter what he does, so I usually end up faking it and I'm convinced he knows I'm faking. It's tearing me apart, I love Jack to bits, and I don't want to lose him. Over the last few weeks I've tried very hard not to use it but, like someone trying to give up smoking, I simply can't resist it and I ride the thing like some frustrated, sex freak and then have deep regrets afterwards.

Every other Saturday Jack goes to the football with his best friend Tommy. Tommy's girlfriend, Liza, usually comes around and we have a few glasses of wine and a general update, natter. Last Saturday, having opened the third bottle, I poured my heart out to Liza about my fear of losing Jack. She listened attentively and tried to console me assuring me that everything would be ok, I just needed to get over my obsession. She admitted she had never heard of a Sybian and wanted to see it. I could see no harm in it so I got it out. Of course then she wanted to see how it worked, so I plugged it in and switched it on. She was fascinated and then, as you've probably guessed, she asked me could she try it. At first I firmly told her no, but she went on and on till, finally, I gave in.

I thought I was the one who really got excited but Liza was no match for me. It simply blew her away, she came at least three times, using all three dildos in sequence, each time her orgasm intensified till she had the largest dildo inside and the machine at full power, something that was far too much for me. When she was, finally, satisfied and collapsed on the settee I was so turned on watching her that I just had to get on the fucking thing myself and then felt terribly guilty.

Now I have two problems one, I'm still obsessed and I'll probably end up losing Jack and two, Lisa is the same way. She keeps ringing me up asking can she come around, let the boy's go out for a drink! You realize where I'm coming from here????

I have no idea how to solve this problem and it's driving me fucking crazy.