Ok, wow, I have a lot to say here. First off, HUGE HUG. I am only 5 weeks out from finding out my recovering ex cheated on me so I am still very raw so I can relate to your pain right now.
I won't tell you to stay or leave or not have contact, because this is a process you need to get through your own way and at your own pace.
The way I see it, contact is important in order for closure and to help make your transition easier.
The extent that he's grovelling, begging and continuing the lies (saying OW is a liar) shows me he has a serious personality flaw. Addict or not. I know many addicts who are not master liars and manipulators. Most lie and manipulate, but not masters! Actually, every lies so....
In my case, I found a woman's pics on my ex's cell and he gave me half/trickled truths before I walked away. Most people, when caught, feel ashamed of their actions. In your case, he has no shame
My ex didn't grovel, he blamed and was not too nice to me once I caught him and asked him to explain, but he never begged for me back and said he would have left me also had I cheated. He never tried to convince me to stay. Though I would have liked to see more caring and remorse for ripping my heart out.
And I agree this pain is worse than any other pain a human can feel. I think I posted something here that talked about how cheating is abuse and how some people say they were raped and the pain of being raped didn't compare to being cheating and lied to.
The one thing that is true, many addict self sabotage. My ex admitted he did this because our relationship was difficult and we didn't really know how to work it out and i said some mean things to him during our relationship, so in my case, since he was not able to express his feelings, he built resentments and cheated. He even admitted it was done a little out of spite.
My ex has been only 2 yrs sober and not worked his steps. He also told me he was going to work his steps and fix this because he just needs to get better and needs to understand why he did this. Blowing smoke up my a^ss? Maybe, but I can't concern myself with this. For his kids sake, I hope he decides to face his HP and become an honest man.
I'm in Al Anon and working on me. Of course I want to believe him, but believing someone who so blatantly lied to my face and had this affair would be stupid of me. Because of these lies, I have been tearing my head apart wondering how many more there were and how deep his cheating was going.
The only way to believe or regain trust in someone who committed such acts of deceptions are to stand back and let them heal. If they heal and are truly remorseful, you'll know.
People can change, people can get well, but people with a serious personality disorder cannot heal or change.
There actions once you leave speak volumes as well.
If they run out to just hook up and continuing lying and act like filth, then all the better that you got out.
My suggestion would be to get to Al Anon ASAP, get to therapy and ask him to stop contacting you until you can sort this out in your head.
Things happen for a reason, you found this out before selling your home and displacing your son, your HP rocks in this case.
Imagine you moved in with this guy?! ugh!!!
I know you're scared, please keep posting and talking and posting and talk some more