Hi, Lost, welcome to SI, the best place you never wanted to be. So sorry you find yourself here, but you will find that all of us have Been There Done That, so much wisdom and compassion and support from other members.
Please start by reading the articles in the Healing Library.
You need to make an appt. with your physician to get tested for STDS. Yes, yes, your husband told you there was no sex, well, cheaters lie, many of us heard the same bullsh*t story.
The best way to end an affair is to expose it....if you know who she is, you say she is married, you MUST tell her husband what's going on (do not tell your husband you are going to do this, it will only give the two of them time to get their stories straight and make you look crazy.)
If your husband truly wants to save his marriage, he HAS to find a new job. My WH had a long-distance EA with a co-worker, and a one afternoon delight when he was visiting her site, there was no way in hell I was going to tolerate any type of communication....ever. After a 25-year stint with the same company, he found another job.
Your husband also has to be transparent giving you access to all social media, cell phone records, email accounts, work email accounts, voicemails, etc. You get the picture. Accountable for his whereabouts at all times. No more going out with the guys or anyone else at this point, his focus needs to be on you and the marriage.
He says he is done with her
^^^Right now your husband's words are meaningless, it will be his actions that speak volumes, and his first order of business is to send her a NC letter. Second order of business is to request a transfer far away from her while searching for a new job. Third order of business is to get himself into counseling to figure out why he would travel down this path of destruction and drop a nuclear bomb on your lives.
If you have adult children, I'd consider blowing his little secret out of the water. Affairs thrive on secrecy, and anything you can do to bust the fantasy bubble will be in your favor.
It takes YEARS to rebuild trust, ONLY if he is truly remorseful and transparent. He must win you back. Not the other way around. He has to earn your forgiveness. Don't rugsweep infidelity.
In the meantime, take care of yourself as best as you can, meet with your dr. if you are having trouble coping. Get yourself into IC. Eat healthily and get exercise. Do things that you enjoy, gardening, meeting friends for lunch, nails done, anything to take your mind off of this mess.
Know you will get through this, it is going to be a long and painful journey, but just take one day at a time, one hour at a time. Lean on TRUSTED family members or friends, lean on us, lean on a GOOD infidelity counselor.
Hugs.....