Just some general thoughts on this thread:
The "she hit me first" thought -
Okay, she hit him first. Makes no difference. In my personal case, I did hit my ex-boyfriend first once. That was probably toward the end of the relationship, actually. There was so much hitting, to tell you the truth. I do remember once when I just slapped him. It was wrong. It does not make the concept that "this is the only time this ever happened" correct. The logic that "she hit me first" does not connect to "this is the only time this ever happened". There is no logical reasoning there to connect the two ideas - no basis in argument.
Personally, I cannot be led to believe this is the first time, and reading her letter, have basis to believe the history of abuse is likely more the case. Her letter rings of truth.
Second - I would agree that there is evidence to support that she was involved with another man at the time of leaving, or at least shortly thereafter (the baby as proof). However, we do not know if it is THIS man or not - it could very well have been a different other man at first, and ended up this man who is caregiving right now. Who knows. What we do know at this point is that this man appears to have information about her status - that's about it. There could be another man being hidden, who is the friend of this man who writes the emails - which may be why he is able to be fairly clear headed about the situation and also alloting her some share of the blame in the situation. Something about his email tells me he believes he is "clean" in this situation - and I'm not sure why. Could be fog.
Third - growing up in an abusive situation and being in an abusive relationship, as Aph points out, does weird things to your head. Aph is right about the concept of not wanting to leave until there is a place to land. When I walked out, I left for my husband. (I was not married - my boyfriend and I were dating at the time, and I broke up with him to date my husband. Nobody was married!) But I stayed with a BOYFRIEND who beat me, and stayed for three years, when there was nothing to keep me there. The craziness was a warped kind of normal - I know this makes no sense, but when it is what you know, it is what you expect, what you think love IS. Until you find out that love does not consist of being smacked around, that arguments need not involve the breaking of furniture or faces, well......you just don't understand that this behavior is not normal, and life CAN be different.
Unless you have lived this, it is very difficult to understand, or to explain. From her letter, she hits the high points. She looks to have escaped before it was REALLY ugly. And as stupid or crass as this may sound, please don't misunderstand, I think it was not "terrible" abuse - not yet. I think she got out before things went from bad to worse to completely collapsed. She was SMART.
I was not.
SB