Hi Anon
Sorry your relationship turned to crap. 
Perhaps have a good long read on the dating thread on this relationship board
(Dating Thread 140...Why?). This may help you get a feel for the lay of the land so to speak in these modern dating times.
He lied to you to have sex with you. How do you know if a man is lying? The compliments, flattery, worthy seductions can spin one’s head around. It brings a sort of adrenaline rush that can be addictive so one does want to believe it very much. Until you get burned. Now you know.
I got to the point where all men lie ... umm hum, sure, if you say so, isn’t that something? It’s a lie until proven it’s not. All men are married or attached until it is proven that they are not. All men are living with someone until it is proven that they are not. The proof is seeing with your own eyes.
They avoid taking you over to theirs: red flag. They avoid seeing/talking to you (texting is different) you on weekends and holidays: red flag. Texting can be done in 20 seconds in the bathroom or garage or while taking the bins out-so don’t let that be proof of anything to you.
I see it as a duty to myself to validate the viability of a man to qualify to date me. Feelings and heart are locked up for a good long while to let the truth have a chance to be revealed. The seduction script is just lip service to get sex. He “wants a relationship” may just be mirroring what you have said to be agreeable to get him closer to having sex. He is your soulmate, at last he’s found someone that really really “gets him”, you are not like all those others....you get the idea: shallow lip service is easy and free and will get him sex.
Dating and relationships don’t have rules the way soccer/football or kick ball does. Not playing fair is not going to be punished by an authority. The rules for dating and relationships are your boundaries. You want a relationship really badly but at what cost? Your safety, self esteem, personal dignity all up for grabs? No. Don’t be desperate. Don’t rush. Don’t presume anything (especially that a bloke must be single because he is on a dating website).
You got hurt because you did not do your due diligence in finding out who this bloke really was/is. Guys do not come with a Good Housekeeping Seal of Approval.
This may sound like victim blaming, but it is the reality- you need to look out for yourself.
Yes, shame on him. What a bastard. They’re a dime a dozen unfortunately.
I agree with pps who say to tell the wife only so she can make informed decisions regarding her circumstances (sexual health).
Telling her to cause the worthless jackass of a bloke some payback pain is not advisable. First of all, it won’t cause him pain- he will laugh. He has bookshelves full of plausible lies to lay out for his wife.
Second, hating him (wanting revenge) is still a connection to him. The connection is gone, just understand that. Hate will just drain you (emotionally- and stressfully) for no purpose. The holy grail is complete indifference. Like he never existed. His name comes up: who? Oh, whatever. Zero response on your emotions meter. Three months on-you should be there.
Let it go. Do something nice for yourself. 