Use your tail.

Your tail snakes around your leg as you begin to rub your clit, growing fatter with every pulse of your heartbeat. You reach out to grip the bulbous, cock-like end, and are treated to the most peculiar sensation of pleasure. The tail end throbs in your hand, and you spread your legs wide, guiding it into your pussy. You proceed to fuck yourself with your own prehensile demon tail. Your mouth hangs open in awestruck pleasure as both the tail-cock and your pussy are erogenous zones. It's hard to remain conscious with so much pleasure.
It takes almost no time at all for you to climax, soaking your tail in your own juices, which you then bring out to pop in your mouth and taste them. You lament your corruption, but can't deny the pleasure it brings to have this tail to aid you in these times of lust.

You clean yourself up and get dressed.