LOL peppy, at the moment I don't have a 'living'. Perhaps I should set myself up as a therapist, in which case, that will be 50 quid please.
Seriously though, you are in a very tempting situation, its not just the gorgeous sexy bloke, its all the other things that go along with it - you know you shouldn't do it therefore its enticing, no one else must know but you both would know so you would share the secret, sneaking around gets the adrenalin pumping and so it goes on.
I used to work in an environment which was 50/50 men and women and the number of affairs going on were outrageous. Many, many of them ended in divorce, ruined lives, broken homes and hearts.
I personally had an affair with a married man for many years and its not something I am proud of with hindsight. No one ever found out but the consequences of our actions could have been huge, not so much for me (i was single) but for him and his family (3 young children). To this day I don't know what I was thinking except to say that I wasnt thinking at all.
IMO if its not you then it will be someone else, bear that in mind before you go any further.