I can relate to feeling soulless.
Do you express yourself better in writing? Could you offer to write it all out for him?
It is natural, and understandable, for us to withhold details we think will further hurt our BH. If you're doing that, I encourage you to rip off the Band-Aid and get it all out now.
Your BH's hurt feelings, his anguish, unfortunately are normal too. You cannot really help him work through that. The best thing you can do, IMO, is to become a safe partner, to look deep within yourself and start changing the bad parts of you that let you make the horrible choice to cheat.
IDK how far out you are, but everyone around here says the anger tends to spike around 6 months post-DDay. True in our case. After 13 months, his angry outbursts have all but subsided. The hurt is still there, but he had to come to terms with what I did, and work through it, pretty much on his own.
with every answer I give him I see his reaction and immediately begin to back pedal
Yikes. Which may give him the impression that you're lying. Again I'm thinking a full, written timeline, including details of communication, dates, places, as best as you can, may be very helpful. Some people do two versions. An x-rated and a PG-13 if you catch my drift. Some BH's want every sordid sexual detail, others prefer not to know that, but the important thing is...give him the choice.
You already decided you knew best how to deal with your perceived problems in the M, and you blew it, big-time. Now it's time to follow BH's lead, and if he needs you to start at the beginning and fill in all the details, then that is what you do. Even if it hurts, or you're afraid he'll leave you if he knows the full truth.