It's understandable that you are still trying to figure things out. Throughout your S, your H maintained consistent contact with you and now he has gone completely dark. You've hit a new stage and just like you adjusted to H not living in the house with you, you'll adjust to not being in contact with him. It's sad for the kids for them to be learning the truth about their father through his own actions. My S has already figured out that he can't depend on his dad and it's heartbreaking (although I have to say that that is slowly changing for him, so it's possible that no permanent damage is being done).
I think it's great that you have a distraction in bf. But at the same time, without thinking about it too much, maybe you need to try to find some closure on your own regarding XH so he's not haunting your subconscious and affecting your emotions.
I love that you still have hope that things will end on a good note. Shows what a kind heart you have. I think as long as you keep that hope with you, things WILL end differently (even if you're not together). It's just that now is not the time.
"In the end, everything will be ok. If it's not ok, it's not the end."