Why would he be horrified?

What is this infatuation/flirting giving you that you aren't getting otherwise?
Need to figure that out before you can fix it I reckon. Otherwise you'll de-infatuate and still be open to re-infatuation at a later date.

You are in a relationship - could you not have dirty phone calls with him instead? Are you in love with your partner?

'we have been doing rude things over the telephone. Well I have anyway.' Eh?

If he is doing these things back too, why would he be horrified to know how you feel?

you actually done anything physical or is it just all flirting?! am nosey.

Hah, not into that sort of thing but will try. The problem is mainly that I am sneaking around having these implausibly long, increasingly explicit telephone conversations. I feel anxious anticipation all the time, hoping for a text or a call. It's furtive and grubby but I seem to have invested at least my short-term/current emotional well-being into this ridiculous situation.

Imagine him / her on the toilet (unless you're into that sort of thing of course).

Oh god, is it? What sort of fleshing out is needed? Is there not a simple way to uninfatuate oneself from something?

That's way too vague.

I swear I am a normal regularish poster btw.

I should feel shame, but I am having too much fun with what could be a disastrous obsession with someone. I'm in a relationship, he knows I post on here so am probably leaving out too much pertinent detail. I do get quite intense but short-lived obsessive interests from time to time when I find it hard to think about little else, but never with an actual person.

The object of my preoccupation would probably be horrified, although we have been doing rude things over the telephone. Well I have anyway.

Mid-life crisis? Insanity? How do I switch it off?