Wow GG, My W has many of the kind of issues your H has. Childhood abandonment, having to take care of her mother after dad left, she even has abuse issues (male babysitter who ended up killing himself many years later). I too knew about these issues and made many allowances over the years of our M. Now, I too am expected to pay even more (and my D's as well). I really thought she was strong to overcome them, but she never really did.
It's not an excuse. We all have issues and she is allowing the man (her dad) who hurt her and her family back in and listening to him when he tells her that she needs to leave the M. That really hurts as here I did my best to help her get over these issues and she runs to the person most responsible for them! I don't think my W will get through her MLC as long as her father stays in her life. Amazing how much power people give their abusers. It seems like so many of the LBS's are the ones who gave up more of what they wanted in the R. Almost like the WAS just can't get enough from the S to fill the void and it just gets so big they "blame" them for not filling it the way they have throughout the M.
Hang in there GG, I think you will be fine no matter what happens.