Online BDSM and the law

I'm trying to find some information regarding the laws of being a mistress. I joined a website and wasn't looking to be a Dom but I now have a Sub, albeit online. I believe he likes the extramarital side of things and doesn't want to act on a lot of his fantasies but I've got increasingly worried about the law. I don't and won't meet him so I'm not taking money for any activity but our private conversations are of BDSM activities, humiliation (of him) and mocking (him and his wife). He wants to feel worthless and this includes me controlling parts of his life and receiving his money.

I've become slightly concerned at the impact of him having daily messages from me of a humiliating nature and belittling him. Where do I stand in law on such matters? He has a safe word and we have soft/hard limits and the nature of our conversations are for his benefit not mine and are generally the areas he has directed me too that interest him (or a repetition of something he previously described). We discuss acts that are now banned from pornography in the U.K. (I have only just discovered this in my research) such as face sitting. I worry that my messages to him could be deemed as emotional abuse or some form of harassment or break some sort of sex worker law? Advice appreciated, facts very welcome.

Sorry I don't know what the law is on this but by the mere fact you've come on here and asked the question you must feel that this isn't right, in which case you know what you need to do......

Maybe not directly related but this link may help:

http://www.independent.co.uk/life-style/...67006.html

I think you've answered your own question, just by starting this thread.

That link is very helpful, thank you.

Forgive me I should have stated 'relevant advice'. Wether you agree or disagree with what I'm doing is irrelevant and my concern is not a reflection of an 'internal moral conflict'. The law regarding pornography is extremely grey and I'm interested in its application to non-fiction and verbal role play.