All I can say is that feeling alone when someone else is actually there is 100 times worse than actually being alone. Like you say, you have the feeling that your H is deliberately trying to erase you. It makes you feel helpless and out of control.
And in one regard, that's true. You can't control how your husband behaves. You can't make him realise what he's losing and suddenly start fighting to keep you. He actually won't likely realise that until you've gone and he starts to experience the reality of your absence.
Or... maybe he won't. Some people are actually so emotionally deadened they don't feel things to the same degree most people do. So he might not miss you much at all, just because he doesn't have much capacity to feel grief or loneliness or loss or regret. But that's not about YOU not being worth feeling anything about. It's about HIS incapacity to feel.
One thing that a lot of disordered and/or emotionally deadened people have in common is that they lack the ability to anticipate the results of their actions in a realistic way.
So if, for example you were considering cheating on your partner, although you might be drawn to cheat by the potential feelings of excitement or desirability, you would also anticipate how stressed and guilty you would feel afterwards, or how devastated your partner would feel if he found out, and that might well be enough to stop you from going ahead with the cheating.
Emotionally deadened people can anticipate reward – the potential good feelings – but not the bad feelings, especially the feelings belonging to other people. So right now, your H might be anticipating a sense of relief or freedom if you leave. And it might take a while before the reality of having to do everything for himself sinks in, or before he's having to deal with the stress of parenting by himself, or loneliness or whatever. At that point, he might start trying to get you back. Or, maybe he's just so emotionally deadened that he won't really care. That can feel hard, like it's you that there was something wrong with, but truly, it's not you. It's him. If he were normal, he'd be doing more to save the relationship right now.
So go, and don't feel guilty. You'll be able to see and love yourself more whole-heartedly again when you aren't dealing with the oppressive feeling of living with someone who does not really care about you.