If I'm being honest - I've hoped to get a message like that from my ex ever since this journey began.
When we were still 'working on our marriage' and I didn't realize he was still in the A, we had some conversations like this but it always left me feeling, empty. Why? Because I never got what I really wanted from him. Anytime I would go to him with a feeling, a longing or something I thought only he could provide, he left me feeling even less whole then when I started. Does that make sense? I would just be more frustrated because he didn't 'get it' and clearly never would.
There is a part of you that will feel satisfied in someway, that yes, you were right, he did make the biggest mistake of his life. But, it won't make you feel as satisfied as you thought, like others said, you'll end up feeling sad, for them, your family, your healing, all of it. It will reopen old wounds and make you question so much. I dont think it will take you back to ground zero, but it won't be easy. In short, if it's closure you're looking for, you won't get it from him because he isn't emotionally stable. This isn't about you being cruel either, it's the truth that no one can fix him but himself. The cheating spouse is broken in a way that you cannot heal and are not responsible for - it's hard for them to see that.
Having said that, if I got a message from my X like that, against my own better judgement I would go. What can I say, it's still hard to separate all that and maybe a part of me would want to confirm that it was a mistake and that I did move in the best way I could. I would lie to myself and say it's because I'm a bigger person and all about 'light and love' moving forward, forgiving people and sending them on their way, no hard feelings. But the truth would be that love is hard to shut off and I would want to see him, no matter how painful. I wouldn't go back to the way things were, of course, but I wouldn't be able to say no to a meeting.
No matter what happens, good luck! We are behind you and please keep us posted. If you do meet with him, remember who you are, how far you've come and that he's simply a broken person that you cannot fix. It may be hard to bounce back from the meeting - know going into it, it will unleash old pain and feelings, but you will bounce back. Good luck!