Most Helpful Guy
Well for me it looks like, you were his rebound girl? I mean kinda suck but yea seems most like it. So while you were pretty much feeling up the void left by his wife, he went on with very huge plans. To feel everything fine and stuff and when the intial remorse and pain had gone. The reality of things set in and well,led to this. So as much I wouldn't tell it was a lie. It was more of a impulsive act.
There is nothing nice about being the rebound person. Only thing you can do is especially if you, yourself just left a relationship give yourself time to be on your own. With at best parents and friends before heading in to another relationship.
So you did the right action. It isn't going to work out if he hadn't gotten over his wife and especially after showing that acts on impulse. I mean to be fair to him he was down but still it wouldn't have led to anything better. So you did the right thing for you and for him too. He needs healing, can't be done by taking you as a replacement for his wife. Not going to work, so yea you did the right thing.
Give yourself some time too and if you do choose to return back to him. That is your choice. If you don't, then in your next one. Go slow and if the other party rushes, sit them down talk clearly to them to set everything straight if they are serious and all.
Just saying what I think. I am just 20 ><" . This is at best I could think. Hope I could help.