Personally, I’m of the opinion that if you legitimately can’t face up to a difficult task that you know you have to do, if you’ve tried several times to do it right and you just can’t do it, then just get it done any way you can. If that means ghosting on him, then so be it.
Honestly whenever I hear about this kind of thing, most of the time the other person had it coming in some way, shape or form. You’re might not be anxious over this precisely because of what he’s done, but he hasn’t exactly been a paragon boyfriend either, otherwise you wouldn’t be breaking up with him. Maybe he doesn’t deserve it, but his feelings do not trump your need to move on with your life.