I'm hearing a lot of compassion for your husband, which shows how incredibly generous and loving (and loveable) a person that your are.
But I'd echo what
@ladee and
@joeylittle have reflected. Your compassion to him is not the same as loving him as a husband. Maybe you just don't any more, and you know what? That's ok. Oftentimes breaking up, especially long term relationships, is a process, rather than a point in time, and when I read your words and his, I see 2 people who are already a long way into that process, and trying like hell to avoid the pain of "it's really over". Idk, maybe I'm way off.
But you know, as honest as he was about his actions in that email, I wasn't hearing a guy who was saying "I love her to bits and I'm gonna keep fighting my arse off to keep her because I don't deserve someone that great..." What I was hearing from that email was "I've tried, and given up, and then tried again. But I keep lying to her, and hurting her, despite my efforts..."
He doesn't seem to be believing that he can really be the man that you deserve. It's ok to agree with him. It's ok to let this one go.
Again, maybe I'm waaaay off. Either way, it's clearly still hurting you a lot, and I really wish that it wasn't this painful for you.