Hi Mabel May - I have been lurking on this thread (I think I may even have posted quite a while ago) - I am also known to ilovemyteddy so she knows my "back story" and has helped me a lot along the way.
Just wanted to chip in this morning really with love and sympathy for you. Been in a similar situation myself - emotional affair with a MM, where I thought it would be a bit of fun (he seemed initially to want that too). Thought I could handle it, etc etc, then before I knew it, fell hook line and sinker for him.
I know he really liked me but for him, that was as far as it went. Looking back I think my strong feelings which I didn't really hide must have caused him to back off - he had a lot to lose, 20 year marriage, successful business & reputation etc.
It is now over 6 months since I heard from him and he is quite local. I am pretty sure I did fall in love with him, whilst still loving my DH and 2 x DS. At some point however I now know it did trip over into the realms of obsession/infatuation. The OM wasn't particularly emotionally intelligent but with hindsight probably did me a favour by "dumping" me without explanation.
Like you I had thought about him constantly, desperately wanted to sleep with him etc etc.
I have soldiered on with "no contact" and he pain is starting to fade - very slightly but I am aware of feeling marginally better.
My experience was similar to that of ilovemyteddy in that there were issues within me, my background and experiences, which led me to seek attention outside my marriage - in my case I latched on to someone who was friendly and flirty but above all attentive towards me.
How I do feel for you and the pain you're going through! My advice for what it's worth is to seek some kind of counselling to help you get a more balanced perspective on the situation. The whole thing can become a very self-destructive and self-perpetuating mess - you mention the phrase "car crash". I tended to drink and eat too much when really really low, put on weight and became extremely irritable and erratic.
I do think you would find talking to a professional helpful.
I'm now 6 months down the line and still trying to get over this guy but I am making little steps of progress each week, so I am living proof to show you it can be done. Life does have to go on and I am sure you, like me, have family and friends who need a "properly functioning" YOU in their lives. From what I have gathered you sound a lovely woman. The man in question is almost certainly not worthy of you, as I now know my OM was not worthy of me.
I do so hope you can find a way forward. Not sure if any of this helps but happy to post again! Sending you my love and good wishes.