Does anyone have any good advice on what to do once you realize you've reached the end of the line in your marriage?

It has been a long time coming but finally, I think it's time to just cut my losses and accept that our marriage has failed and there's nothing more I can do about it. And now I have no idea what to do with this new situation.

We've tried. Both in our own ways, I suppose. For years. And years. And years. In the end, never really getting anywhere. No progress or any real change for the better. Just worse and worse in slight increments over a looooong time.

I take full responsibility for all the wrong reactions, anger, venting, nagging, stonewalling, exasperation etc etc etc. I am fully aware that I am just as responsible for how things are and for many, many years I made efforts to change my behaviour. I wish I still had the strength to do so, but I realize that I don't. I am utterly exhausted and unable to put in the effort or keep my anger from poisoning my words.

I admit that I started withdrawing and "letting things go" in small steps several years ago. That's absolutely on me. I wish I hadn't, but at times it's the only thing I knew how to do to keep from imploding. I retreated into a "I don't care - let it all go to hell then - not my responsibility" attitude about more and more things, because I felt that nothing I or we tried made any difference anyway - so why bother.

Nothing that was said, done or agreed upon made any lasting difference at all. Nagging had no effect. Not nagging had no effect. I'm not sure at which point he checked out on us - or if he was ever really connected in the first place. But in the end, I feel I've turned into air. Like I don't exist and nothing I do or say even registers.

I used to feel cheated and let down. Now I'm just too tired to even be angry or sad. I'm just absolutely numb. Totally numb.

Unfortunately, my spouse is unable to take any long lasting responsibility for the ADHD or anything concerning me or our marriage, and has never done anything to get any other help other than meds for the ADHD. For him, the meds, I believe, make coping with life internally a bit easier, but they really have no effect that is outwardly apparent. Actually getting things done or taking responsibility for things gets no better. In the past, after I totally blow a casket, behaviour changes on my spouse's part come into play for anything from a few hours to a few weeks. Then it's always been comfortably back to the status quo. Sort of like a sigh of relief like "There, now I did it. Now you can't be mad at me anymore and we can get back to normal again". After the umpteenth time, I just quit caring one way or the other to cope with the never ending disappointment.

I wish I could once again pick myself up and keep on going. I wish I could tell myself "it will get better", but doing so, honestly, feels insane. And I'm past the point of being a nice person when I am with my spouse. At this point, I am unable to control my feelings and even when I try my utmost to be nice, the anger seeps through and I hate that I can't stop it.

The really tragic part is that I'm sure there would have been an abundance of things that would have made things better, but neither of us is or has been able to do them. My spouse mostly because it would require some effort and a commitment - me mostly because I'm no longer able to keep myself strong on my own while waiting for that commitment to magically appear from somewhere.

But what do I do now? Where do I get the energy to carry out everything that a divorce entails?