First, a hug for your (((((NothingbutAshes)))))
I'm so sorry you have been betrayed, and betrayed, and betrayed. I can feel your pain through your post.
We all know the misery, confusion and brokenness adultery brings.
To recap what I got from your post:
Your H has been unfaithful and insensitive to you throughout your entire M, from what you said. At one point, you asked him, ďThis will never end, will it?Ē and he said ďIím afraid not.Ē
Then he continued escalating his behavior.
Finally, you decided you had enough, and began preparing to leave with your children.
Now he is professing his love for you, and begging you to not leave.
This has taken 8 years....8 years.
Your H sounds like a Sex Addict (SA). That is his issue, not yours. Only he can fix that. You need to take care of yourself, and you have started doing that already.
He needs to begin to face that, via IC, reading books and work a serious program. He could start by reading. Hope and Freedom For Sexual Addicts and Their Partners by Milton Magness.
Your WH is not going to change overnight. For 8 years he has had his cake and eat it too. I know you L him, most of us BSes here L our spouses, in spite of how they have hurt us.
If you want to make one last go of it, you need to set specific boundaries, and let him know that if (when) he breaks one of them, the M is over and you will be filing for D.
1. NC with all people, websites, etc. that participated in his cheating.
2. Give you his secret phone. No more secret phones...only the ones on your mutual phone plan.
3. Passwords to computer and all websites. You can check his email, history...he cannot delete history, ever.
4. Timeline with names of all people and websites, etc. he used, and give it to you.
5. IC to work on SA issues.
6. 100% transparency. You have access to everything. If he gets any phone calls or emails, etc. from sex partners, he tells you immediately, and he remains NC.
7. Get a free consultation from a lawyer, to find out about your rights if you D. Knowledge is power. You won't feel so lost once you know your rights.
If your state is not a no fault state, make copies of all evidence of the cheating that you have. It will help you in court. Begin drawing up the D papers, so you will have them ready if he cheats again. (He will probably cheat again, since he has had at least of 8 years of habit already formed.)
For yourself, go to your doctor and get AD meds if needed, and something to help you sleep. Drink lots of fluids, even if you can't eat.
I started smoking too, at one point, due to the stress and unpredictability. Smoking was a predictable routine that was "mine" and which lasted a few minutes when I needed it. Eventually I didn't need it anymore, and the nicotine made me feel worse than the routine made me feel better. You'll be able to quit smoking again, when your world evens out.
AND IT WILL. Stand your ground, and don't accept 2nds anymore. You are worth it, and you are strong.