It is possible, and worth it IME, but it's hard going.
We're 2 years on and we're getting married this year (been together a LONG time).
My DM likes to throw it in my face every now and again (she did this a couple of days ago, even though she loves my DP) which is nice
, and people who know, going through the same thing may seek you out if it happens to them (also happening to us at the moment)...So it's not really something that you can forget. You have to learn to live with it and accept that it happened. If you can't do that you will argue constantly as it won't just dissolve and go away.
My initial reaction was to kick him out and forget about him as I didn't want to be 'that woman' - the stupid one who forgives.
He was away for 4 weeks, we did some talking while he was away, I told him I wouldn't even speak to him if she was still in the picture. She was phased out rather than blocked out initially, after she tried to stay in contact quite forcefully, she was blocked out (he didn't move in with her, he was staying in a friends, which I know is true). I thought she'd been completely blocked from the start and this caused a few problems when I found out she'd been emailing and getting her friends to call my home pretending to be service calls if I answered but passing the phone to OW if he answered, and they'd met up in a park on her lunchbreak so he could tell her what was what and 'Sorry, but that's it' (I'll never know for sure what happened at this meeting, I have to take his word for it and I trust it was what he said).
I needed him to be away. I wanted to see what happened, where he went, who he turned to, who he missed. It wasn't OW. This is the only way I actually felt his remorse. He will have loose ends to tie up, mess to unravel, time to get his head together and come to terms with the fallout - I just didn't want him to do that under my nose. It was his to sort out. My advice to you would be to do the same - take control of the situation and make him work to put this all back together (if that's what you want - you may decide you don't want him). Good luck.