Since no one has responded, I'll give it a shot
Based on what I have witnessed myself, the only people who successfully turn an affair into a long term committed relationship/marriage are those who weren't serial cheaters.
Once they cheated they were pretty shocked by their own behavior and actually either fessed up to their spouses and initially jumped through all kinds of hoops to "fix things", OR they just immediately made plans to leave their spouses.
In other words, being deceitful was not normal behavior for them.
So when they decide to be with the person they cheated with long term they don't struggle with "trust issues" because they don't see themselves as regular cheaters. They see themselves has only having cheated for THAT particular person.
I think two serial cheaters trying to achieve a successful relationship have their work cut out for them.