I think that if this thing is getting to be a constant affair of heartaches and frustrations coupled with a daily dose of physical and emotional torture, then this thing you have going on will never give you the clarity you guys are aiming for. My point is, ... What's the point of sticking around,
Wag Alamin?
The Right Decisions aren't suppose to be difficult to come by. There's a simple series of Q and A that determines where your decisions will lead you to. If say your decisions are causing more problems, causing more complications than it does anybody good, then sure enough your way towards correcting a fault is messed up.
Let's take a look at your Penance in particular. You may feel that you deserve to take all these punishments because you did cause all of these, but is it helping your husband? Is it helping your marriage? Will all the battery make up for what you've done? Or is it simply driving your husband crazier and crazier thinking about how he was betrayed. Crazier and crazier thinking about the fact that he can't undo it anymore. Even crazier knowing that despite all of that, he still NEEDS you, wants you, but since he is hurt he has to take it out on you. What should drive him over the edge is that he still cares but he can't help but hurt you as if he doesn't. Then it all points back to your cheating. .... Which in the final analysis, can't be
undone anymore.
Then there's this threat of him killing himself. And that hurts you big time because if he ends up killing himself then it all goes back to your fault for betraying him. So you are stuck. It's either you live a life of constant abuse, or a widow whose husband committed suicide because his wife cheated him. ... The problem here is THIS:
Those aren't your only Options.
I think that when you've crossed lines that aren't suppose to be crossed, all hell breaks lose and try as you might, relationships can be seldom salvaged. The more you try to save it the more things get complicated, the more the problems pile up. Before you know it, spin-off problems start emerging and like a fatal disease what very often kills the patients are the complications of the disease and not the disease itself.
So you probably thought as a form of penance you'll sacrifice your own pride, happiness, freedom, and even health just to pay for your mistakes. You probably thought getting battered physically and emotionally would cleanse you of your sins and maybe save your marriage. It's a gallant stand, really. It surely means you are a strong woman willing to sacrifice her own happiness. But if sticking around would only cause the aggrieved party to turn into a frustrated crying monster then what you are doing is only leading him into a world of more pain. You are actually leading him into a pit. Simply put, Being Strong doesn't always mean staying put. Especially when your presence will only cause further problems.
Had your husband been stronger and more determined like a lot of other Brutes

he would have thrown you out, asked you to leave, asked for an annulment/divorce/a refund

. That would have been wrong too but it would have been much better than keeping you for Beating Purposes. Maybe things would have been less complicated that way. If say he realizes that he is willing for forgive you, then it will come after you two have had the timely break. If say you realize that you really did him wrong, it will come from the pain you inflicted onto yourself and not via the constant beating you are taking. Nor that constant mental torture he experiences because of his insecurities.
My point is, at this stage in your marriage and union, you two are
NOT good for each other. Together, you will only cause more harm to each other than any good. At this point in your marriage when one cheated and one plans to take it out on her through punishments or suicide, then you know you've hit a fork in the road and the only way to live through this one is to choose separate paths.
You are the one who started this, right? So the smartest thing to do right now is to be Strong and also Wise. Put your efforts in coming up with a settlement which is likely to be a separation, trial or otherwise, which will give you two the space that you need. Space to grieve all by your lonesome is good. Space to be frustrated without taking anybody along the tailspin. It'll be sad for sure, but sometimes a person deals with frustrations better alone.
In the process, try to ensure that he doesn't kill himself. If by any chance the wrist slashing he did resulted in nothing more serious than flesh wounds, then he probably is more determined to get in your head than actually snuff himself. Guys are more likely to shoot themselves in the mouth or hang themselves than slash their wrist. It's suicidal women who slash themselves more. Sorry for sounding so insensitive, but that is true.

If you feel that you want/need to save your marriage, then keep in mind that the longer you two hang onto each other the more crimes you two commit to yourselves. The lesser your chances of saving your marriage and the more the chances you two have of killing each other, or drive each other nuts.
My point is Wag Alamin, there is the Right Way to be Strong. And the Right Way to correct a problem. If you are really determined to do Penance, then I say "saving your husband", "saving yourself", and "saving what's left of your lives" is currently the best Penance for you to work on.
If I may call a Spade a Spade:
"What you did has the potential to end your marriage". That's it. But it doesn't mean that it's the end your lives and the end for the happiness you two deserve.