I think it's a big deal that you noticed the hard-hitting line 'you must be willing to lose your marriage.' I think you should sit with your reaction to that for a bit and see where your thought process takes you.
You are very early on, and it takes us (BSs) a long time to even be able to see straight again, never mind be confident in our decisions.
I will share with you (in hopes that it helps) that it was not until I was genuinely able to consider the possiblity of my marriage ending (for real too, not just words) that I even began to heal. For me, that meant a lot of writing out my thoughts and laying down some real plans for the possibility. I spoke to a lawyer about my options, talked to my family members that it would affect, and finally, after a ton of thinking, writing and narrowing down, communicated those to my H. I told him about my intentions if we separated. I told him that I would file for full custody of our boys, but that I never EVER intended to keep them from him or him from them. I had a lawyer draft a document that clearly outlined what we were entitled to of the house, and I let him know that I intended to try to keep our home for the boys by renting the basement. I also wrote a contract for him to sign that clearly laid out exactly what I would do if he acted in certain ways. I asked him to carry the contract in his wallet, and I let him know that it only held value because it was 100% true - if he screwed up again, with all the work and knowledge he gained, I would end our marriage the instant I found out. And I still will. We are heartily and happily in R right now, in fact it's the best our relationship has ever been! If I found out that he even contacted the OW and lied to me about it today, our marriage would be over without question. And that is sad for me, but at least now I can believe in something. I can believe in myself and that decision, and it gives me one tiny piece of solid ground to stand on in an ocean of uncertainty. Perhaps that's the general direction you need to follow now.
You are not alone, we're here with you.