I'm back after finishing up the semester and having my D all weekend. I'm caught up now and the biggest thing I still notice is how you seem to continue to ride the roller coaster w/xBF.
If he calls or contacts you, you are happy, but if there is NC, you are sad and blue. That is the part that troubles me, my dear. I'm not sure what else to say, but to try and avoid any alinalizing, and to not talk at all about Helen.
The more you find out the more it seems to tear you up inside, so if possible, try to avoid knowing anything about his relationship w/her. Having your friend Cher find things out for you about him also just prolongs the agony in you and puts you back on that roller coaster again. Besides, if he ends his relationship w/her, you'll know soon enough. If you can act "as if" it doesn't bother you, soon enough, it really won't.
People also say if you want to get over a relationship you need to have anywhere from 1-3 months of NC before you can feel good on your own again. I'm not suggesting you completely walk away, but honestly, a little NC for you right now may help your own spirit to mend.
As Jeff so artfully quoted Woog, "he is broken"...very, very broken. Thus, he will continue to be very inconsistent. He can't do consistency. Instead, he'll fade in and out of the picture w/you for quite some time to come, so let his roller coaster pass you by and you just stay on the platform.
Let go of the rope. Be his friend, but let him go on his own journey and you, in turn, go on yours.
I hope this makes sense and comes across w/the love it is intended, my friend. We are both in the same boat when it comes to having a very different Christmas this year and like you, I'm not a big fan of it either. However, I know it will pass and I'll use it to grow and become better for myself and my D.
I know you'll be ok too. As painful as it is to think about, in time we'll all be better for passing through the pain and not avoiding it.