Congrats on the 2nd Chance! Keep in mind this is a completely new relationship and you'll have to continue to stick to the boundaries you've set up for yourself while you two were apart. Don't forget those, or the time you were away will be meaningless.
Also, you have a big psychological hurdle to climb concerning the ghosts of Helen. She'll be in your thoughts as long as you allow her to be there. I'm quite sure it is an easy thing for me to "tell" you to do and I still struggle at times w/XW's "men" (i.e. the Snake, and the apartment complex guy) when I see her b/c it makes me sad and angry at the same time.
However, I'm able to move past it in mere minutes (sometimes seconds even), so it doesn't weigh me down. That said, I'm also never getting back w/her, so I'm in a bit of a different world than you are.
Regardless, she'll only be as powerful in your new R as you let her. BF has guilt over it, that is plain from your posts. When you are ready to completely forgive him and her, you'll know it.
Remember, forgiveness is for yourself, not for others.
Good going. Keep your head up and eyes wide open! Still make him chase you a bit. It is good for him to put forth the effort this time around.
RTL PS - Ignore anything you'd like to in my posts. As always, just playing Devil's advocate and trying to get you to think about all possibilities. Never intending to be a downer, my dear.
