You are right about one thing, they will never truly FEEL what it feels like to be the BS. However, they can empathize with our pain and understand the depth it goes to. How? By telling them.
I spent the first 18 months or so telling my H about every single trigger I had. I told him what the trigger was, WHY it was a trigger, what it reminded me of, and what it made me feel like and why as well. After 18 months, there weren't really any new triggers for a very long time, so I could just tell him "I'm triggering over xyz" and he would now know why, what it felt like, etc., because I already told him a lot.
If I had a new trigger, I would tell him the details about it. Heck, just yesterday we had a new trigger talk. We moved back to A town a few months ago. Up until we moved back, I didn't have to worry about running into any OW ever, and it was blissful. But that's not the case anymore. So we're at the waterpark with our kids yesterday, and I was watching all the happy people, and I noticed many women who fit the general description of some of his OW. So I asked him "do you think you would ever recognize any of those women". I didn't tell him which women, I simply said, out of the blue, exactly what I posted. He said "honestly, I really don't think I would at all". He knew EXACTLY what I was talking about, even given the randomness of the comment. We were having a great day, and we continued to have a great day after that.
I know that my H has felt the level of betrayal himself as well. It was about 5 months after DDay, and we were having a regular conversation about the kids, and he suddenly remembered how he had taken them to the park when they were really little (like 5 and 3ish) because I was sick. He took the laptop with him, and he spent the entire time cruising for women online. Our kids, HIS kids, kept asking him to push them on the swing, and he told them no because he was too busy. When that memory came to him, it hit him like a ton of bricks and he collapsed and started bawling and sobbing and shaking. I believe he felt what the betrayal felt like that day, because he realized that he had betrayed himself, his children, and his family all at once, and it hurt him to know that someone treated his children like that.... and that someone was him.