The above sentence... haunts me. When i first heard it from my W, it hit me pretty hard-- I had never hear anyone describe their frame of mind that way. (The exact words my own W used were ""I feel like I'm dying inside.") What hit me even harder, of course, was my discovery, less than two weeks later, that she was involved in an affair with one of my closest friends.
But whether it is actively engaging in an affair or simply "leaving" the marriage, it never ceases to amaze me how many marriages get so far down that dark road before either spouse takes action to shake things up. My own marriage was a sex-starved marriage (SSM) for several years prior to my W's BD. She had even come to me twice previously saying she was sad, or upset with the way things were between us, and once, well prior to the affair, had even said she was going to leave and half-packed her bag. Both times, she relented, and we just... kept... plodding...along. Until that final bomb drop, when she was obviously much more strident in her statements to me and shortly thereafter was caught in her affair... then things started happening fast. Boy did I start changing things up after that (though it took me just a bit to go from weeping/pleading/begging/appeasing to hitting me stride as the stronger, more independent guy that I had been years ago and that i knew i could be again). Problem was, she had finally stepped out, seemingly for good... at least that was her intention and she was acting accordingly. Fast forward nearly a year and a half later, when our reconciliation/counseling attempts were at least somewhat promising but still, in many respects, just... plodding... along. Until I found out she was still entertaining periodic phone calls from OM... and I blew things up myself by telling her i was done, that i wanted her gone, and by walking out on her. And that was the beginning of real progress between us.
I guess what i am trying to say is that it seems like marriages too easily fall into this state of disrepair and unhappiness and non-fulfillment, or even outright despair, and inertia just keeps either party from doing anything to save them. By the time one party finally speaks up strongly enough and/or acts out... it is often too late. I'm certainly not blaming my W 100% for the state our marriage had reached (nor am I taking 100% of the blame), but it seems to me that if either spouse took catalytic action earlier in the marriage-- and I am talking something that really gets the others' attention and makes clear that the marriage is on the precipice of being over, that more marriages might be saved. How that happens, I have no clue, it seems like people and marriages seem to fall into the same patterns over and over and over... but i do know that as bad as things had gotten in my own marriage, as hopeless as it (and I) must have seemed to my W, and as indifferent as I, too, had become in many ways... I did not, at the end of the day, want my marriage to end. I had been in love with this person, once, and could be again. I truly think i could have been convinced of the depth of the problem without being smacked over the head with an affair-- if I had ever been convinced by my W that she might actually leave. Same way with my W, later on. I don't think it really hit her how much she wanted the marriage, and me, until it became clear that I might actually leave. So maybe that's the key. It is said here that "they will never find you so attractive as when you are walking away." Maybe if more spouses knew how close their own spouse was to leaving them and ending the marriage before they actually decided to leave, more could be saved.
You're apparently already past the phase of wanting to save the MR... Or not(?) If not, maybe give some of the DB-ing techniques a chance for both you and your H. Instead of dwelling on how much you "dislike" him... try to notice any new positive things he is doing. For your own part, instead of dwelling on your misery, find ways to "GAL" yourself, or change old habits that might have been hurtful to you and/or your H (what we call "180s"). Try to find inner joy and confidence and love for self. You can't have a good relationship with someone else unless you already have one with "you".
Anyway, hope this is in some way helpful. I realize that i wrote an entire book, above, and likely gave you very little helpful advice. But, as it did when my own W said it, your "feeling dead inside" statement resonated with me. It likely did with your H, as well. Unless things are completely, irretrievably off the rails... why not think about giving him a chance? Or at least think about putting things in a holding pattern while you work on "you" for a while.
Best of luck.
H53/W51, R-ing 4/'18
"Do not arouse or awaken love until it so desires"-Sg.of Sg 2:7
"So oftentimes it happens,that we live our lives in chains, & we never even know we have the key"-Eagles III 1:3