i get it...it is tough for sure.  make sure you have boundaries to protect yourself my friend.  i know it can seem overhwleming so go at a pace you feel good with.  

the reality is, there is hope but only with expert help. the ems weekend will be the best bet which you can find here:  https://www.affairrecovery.com/product/ems-weekend   he will need an expert like Rick and Dr. John Haney to assess him and lay out a protcol for you both.  there is hope, but not if you don't access experts my friend. it's just the real truth that lower level/general/inexperienced therapists etc will be eaten for lunch by a serial cheater and narc.  hope you will give it some thought. 

what we typically advise and do ourselves, is to do personal work and then come together periodically, depending on the temperature of the communication at that present time, and talk about what our personal work is doing for us.  

if you're having a difficult time communicating, it's tougher so typically once a week.  if things are going ok for the most part, at least once or twice a week, it's great to come together and talk about what your personal work is showing you and helping you see differently.  then you can affirm each other and focus on the positive.  that typically makes some good headway as you progress through the process.  does that make sense?  again, it's about the positive and what your own work is doing for the way you see your spouse, your situation, your choices, etc.