Honestly I have dealt with many domestic abuse situations and I don't believe I've seen and really cannot imagine a situation where the perpetrator of long term physical and mental and sexual abuse sat down, after the person had gone and wrote detailed emails to their now fled spouse, NOT begging them to come back or promising to change, or even threatening to make them pay in the future, but rather where they confessed every incident of abuse that has happened in the past.
And then explained in greatest detail how they managed to convince all friends and family members that the other person was the abuser, or that nothing wrong was happening. Oh yes, and in the meantime they also confessed to and bragged about having committed several other crimes. He told her how he is a con man and has scammed the friends, family and the government. He isn't a very bright con man, from the sound of this. This story just doesn't sound right. And as it has been pointed out, they just don't take emails as evidence of abuse and rush out and throw someone in the pokey because he allegedly wrote them.
I think this person has gotten a really confused and distorted interpretation of what they were actually told by the local police when they carried in these really amazing confess-everything-I-ever-did wrong-in-great-detail emails.