Divorces based on the Grounds of Adultery in MD will get you into court about 6 months earlier than waiting it out for the one year of separation...(at least in Calvert it's that quick) you can file now, be in court within 6 months... or wait the 1 yr and then it will be another 6months for your court date from the time you actually file for divorce.
You know what you know - it doesnt matter what any of us know or think. Do what is right for YOU. You actually sound like you could be the wife of a guy that works in another office in my building....where everyone but the wife "knows". very sad. however, it's not "her" fault... he's the one that made himself available to her. She didnt have a vow with you, he did. Not all marriages are doomed for divorce - i tried to reconcile and make it work - but it has to be both of you realizing your marriage is doomed...AND both of you working to make it right. He has to be willing to live transparently to rebuild the trust - but apparently, you've had that discussion and attempt and he chose not to do what he said he would. One person cant make a marriage work - i think you know where you need to go from here - i just hope you have peace about it and the support of family and friends like i did when it was my time to make the move. You'll be better off -- in time. Good luck!!