I'm a slim, 31-year-old woman attracted to older, obese men – the uglier the better. I fantasise about being passed around by several of them. The thing that really turns me on is the idea of having to lift their stomachs and search for their penises, which are always difficult to find and a bit on the soft side. I haven't mentioned this to my fiance, because I think he would be horrified. Our sex life is fine, but I use the fantasy to help me climax. I feel guilty – what made me so sick?

Your erotic imaginings are private; you don't have to share them. Fantasies develop in different ways. Some are generated from real events or images, while others are creative imaginings that arise through need, longing or even trauma. Consider searching for the root. One aspect of your fantasy that might be relevant is the fact the imagined men are not really ready for sex. Somehow, you've developed an turn-on that keeps you safe, where despite being "passed around", you still retain control. Perhaps the men's perceived unattractiveness also helps you feel safe and releases you from the anxiety of being physically judged yourself. So your fantasy is not the product of a "sick" mind, but may be a clever creative exercise designed to help assuage sexual fear and a negative body image.

• Pamela Stephenson Connolly is a psychotherapist who specialises in treating sexual disorders

• If you would like advice from Pamela Stephenson Connolly on sexual matters, send us a brief description of your concerns to private.lives@theguardian.com (please don't send attachments).