I was checking my "other folders" section on my facebook account tonight and found a message with photos of my STBXH with an other woman and a bitchy message letting me know about their 15 month relationship which started 4 months before I got the "I don't love you" speech.
I posted on here at the time (I don't know how to link it) and got some solid advice and I'm hoping for some more tonight...
He told me in October 2012 he didn't love me but I couldn't get the courage up to ask him to leave until February 2013 
So he will be out of the family home 1 year on the 28th February. I went to counselling, I leaned on my friends and attended Al-Anon (for his and my parents' alcohol issues) and I have been starting to feel scared to say it- a wee bit happy. I spent Valentines night with 2 friends having drinks and a laugh 
Now I feel like this has knocked me back again. He is such a cliche and I'm a stupid idiot for ever believing that he wouldn't do this to me.
So what do I do?
Do I reply to his now dumped mistress (she sent the message because "he has hurt me and he deserves to be hurt too" 
Will it help in the long run asking him for the details: all he will say in the phone (after denying it until I told him I had the photos) is it was a mistake and he will spend the rest of his life regretting it
is her facebook message enough to get a divorce for adultery?