I don't know if this is helpful or not...
It took me years (as a WS) to get past my own bullshit enough to actually feel empathy for my BW. And having been on SI for years, I've seen that same pattern in other WS's over and over again. The thing is, it takes an incredible amount of entitlement, selfishness and lack of empathy to have an affair in the first place. That's not something you just "shake off" as a result of having been caught. It's a character flaw. (To be clear, that's not a judgment on WS's. I'm not saying they are bad people at heart. Most of the time, they are just very, very broken people who lack the skills and experience it takes to be a better person.) Changing that takes a heroic amount of effort, understanding, humility, and sacrifice. Which is why most WS's never succeed in changing.
Most WS's are capable of "saying the things", such as "I'm sorry" or "I had an affair" or other statements that, to an outsider, might seem like a heartfelt apology. But they aren't heartfelt, or more accurately, they aren't heartfelt towards YOU, the BS, the victim. Most WS's are sad for THEMSELVES. They feel badly for cheating. They feel badly for getting caught. They feel badly for screwing up not only their marriage but their affair as well. My point being, everything they feel is about themselves, not about the person they hurt, not really. Worse yet, the sorrow they feel for themselves is misguided. They don't think to themselves, "Gosh, I really denigrated myself there. I gave up my own self-respect and dignity, for nothing." Instead, it takes the form of self-pity. They are sorry for ruining their own lives moreso than anyone else's.
It can be difficult for a non-WS to understand this sometimes. For most people, integrity and empathy are part of who they are. If you bump into someone in a restaurant and end up spilling a drink all over them, the result is that you feel badly for THEM. You apologize, you help clean them up, you offer to pay for cleaning or new clothes, you buy them a new drink, promise to be more careful, etc. In other words, we "own" what we did, and then we do all we can to both maintain our own sense of dignity, while also showing empathy and care for the other person and the result that our actions had on them. Which, same as you, is all most BS's are really asking for from their WS's. Just "own it". Just show some concern and actual care about someone other than themselves. It's not really the apology that matters, it's just the fact that you, the BS, seem to not matter to the WS. It leaves most people feeling unseen, unheard, and most of all, uncared for. It makes us wonder how we could care more about a stranger in a restaurant than someone we married and love and have built a life together with.
You're not going to get the apology and the understanding that you are looking for until (and if) such time that the WS does "the work" and makes serious changes and growth in their life. In the most simple terms, you can't show love for someone else until you love yourself first, and a person that is buried in shame and guilt and entitlement and selfishness, most certainly does not love themselves. They loathe themselves. People who loathe themselves struggle with self-love, and often lack the skills to "self-soothe" or feel good about themselves regardless of what others think. So instead, they get their love and happiness from others. They need other people to like them, to love them, to tell them that they are smart, handsome, funny, talented, whatever. Their self-worth is predicated on approval and compliments from others. Which seems to work just fine... until it doesn't. The problem is, the moment that "flow of incoming love" stops, the WS finds themselves empty and full of self-loathing again. I often describe it as a gas tank with a hole in the bottom. As long as you keep pouring gas in, it's fine. When the flow stops, the tank empties, fast, and the WS is left in a panic, and in a state where they feel overwhelmed, and defined, by their own lack of self-love. And what's the easiest way to fix that? Go find someone to tell you that you're great, someone who will put you on a pedastal, make you feel special, treat you like your presence in their life makes their life better. You know... an affair. (Which, btw, is why affairs have nothing to do with "love". It's about using each other to get the approval we need, even if it's fake and fucked up.)
If you choose to stay with your spouse, then my best advice is to insist on them doing the work. Make it a requirement of R. They have to figure out what it is in their lives that made them so needy in the first place. If they lack the skills to self-soothe without requiring others, then they need to develop those skills. They need to understand what factors in their life (in most cases, this goes back to childhood) contributed to how they feel about themselves today, and have a plan of action to "fix" those things. This is no small feat, and requires courage and commitment, and a willingness to fail and yet keep trying. But it CAN happen, and if and when it does, it can change the dynamics of the relationship in positive ways. I just want to be clear that there are no gaurantees. A lot of damage has been done. Your spouse might do the work and become the world's most perfect person, it still may not matter. I try to impress on most WS's that the work is worth doing, regardless of the marriage outcomes. Until they make those changes in their lives, it will continue to affect all future relationships (work, friends, family) as well as how they feel about themselves.
I hope you find what you are looking for.