I know how you feel about that "rabbit hole" and I'm so sorry for you. I've been on this ride since March and its tough not see down the road without the gloom and doom. Back in June, my W felt we wouldn't be together by summer's end despite all the changes I have made! ... and yet here it is at summer's end and she's made no mention to me about leaving and even tho its been rough at times (like just last week), there are also glimmers of time when I feel we will still get past all of this. (like now ... boy I have to find some time to update my thread)
Stick with your changes. I know how hard it is sometimes when you don't seem to get the recognition for your efforts, but don't let resentment set in. Remember that you change for you first and foremost. If you like who you are now seek gratification from within and you'll know your efforts are not a waste. He is still resisting your changes are real. He needs more time to be convinced. Think of his 80+ hours as a test of your resolve. He is looking to see if the old "you" will surface because of it. By letting him know you are filling your time with what you enjoy doing and not placing any pressure on him by bring up the amount of time he is working. Does his job compensate by granting additional time off at a later date? If so, maybe just mention something you would like to do together when such time is granted as something enjoyable you both can look foward to help during this trying time.
In the meantime, to get thru it ... take it day by day ... keep active and fill the time he is not there with ways that you enjoy doing. If "competing" with possible OW, helps keep focus on presenting the better you to H, then stay in competition mode. I find that works for me in helping me from lashing out at W in poor DBing form. I'm always focused on presenting myself at my best. Does it suck? Sure it does!! ... but look at it this way. It is the motivation needed to consistantly pratice those changes until they seem second nature to you.
Quoting Jackie: he feels I grill him about work and I'm not sincere in asking about his day, just doing it to go through the motions.
OK, so a 180 is needed to break that preception and it involves how you present yourself when talking about his day. I don't know about how things were and I'm sure you are doing some/if not all, of what I'm about to suggest, but you need to break the preception that you are "going thru the motions" and make it feel you are sincerely interested. When he talks about his day, look him directly in his eyes, so he can see you are listening to every word. Don't get distracted when he is talking. If something else does demand your immediate attention, ask H to pause for a moment because you don't want to miss anything he says. Validate so he knows you are tuning in and listening.
Hang in there Jackie and try to consider this just a temporary setback. Re-focus your DBing efforts and you will get thru it.