So I actually just signed up to reddit to make a post to get advice about my own relationship. Then I found your post. Luckily I'm not married, but I am in a relationship of 4 years and after reading what you just wrote, I have to say that I'm in exactly the same relationship you are, only in my story I'm your husband. I haven't left her, but I'm at the point where she's more or less broken me and I feel like its coming. I wish she could read what you wrote, because I know she's going to write exactly the same thing if I follow through with breaking up with her, even down to the excuses. You weren't blindsided here, you knew this was coming and chose not to act on his grievances as playing coy was easier.
I can't pretend to know what your husband is thinking, but I'll respond to what you've written having a girlfriend exactly the same as you.
The reasons are the same: he's tired of hearing me put myself down, and of feeling like I'm not interested in him. He's not entirely wrong: in the past few months, I haven't been terribly interested in anything.
Do you understand just how frustrating this is? To your husband you acting distant just looks like a lack of interest in him. To make matters worse, you're pushing your lack of self esteem on to him and no doubt breaking down his confidence in the process. You saying you haven't been interested in anything and then including him (my girlfriend uses this line every time we argue about it) doesn't excuse you. I know in my situation that my girlfriend's lack of interest has become so habitual that I've also lost interest. Only my lack of interest isn't mood related like hers and yours. Mine (and no doubt your husband's) is now permanent. You conditioned this reaction from him.
I'm not the type of person to ask for help. I have always been very independent, and reluctant to let people in, and loath to inconvenience anyone, and hesitant to count on anyone but myself.
Again, my partner is exactly the same as this. Here's the thing though. Are you trying desperately not to be an inconvenience or are you just being self centred? You could easily interpret what you just said as simply you being self centred and only wallowing in your own problems and stresses 24/7. As I said, my partner says what you said all the time, as an excuse to everyone when she's cold or unintentionally a jerk to them whilst trying 'not to be an inconvenience' (read this as just being rude).
He's not been very talkative or affectionate lately, but I figured that it was work stress, and I tried not to bother him too much. He says he's been thinking about this for months, but I can't help but wonder why he didn't say something the first time the word divorce crossed his mind, rather than let it fester until it was irreversible.
Now here's where I'm at in my relationship now. He's told you what problems he had in the relationship before and you let them continue. Chances are that you've been so self-centred, always thinking about your problems and neglecting him in the process that you failed to catch on to whatever signals he was sending you as an ultimatum. I don't think he left the decision this long just to let it fester, he no doubt left it this long to give you a chance to make it up to him, and you didn't.
My partner's cold nature whenever she is stressed or anxious has driven me to a point where I don't feel like being affectionate to her anymore. Why on earth would I? At this point it is up to her to make an effort or apologise. In my situation, as with yours I've accommodated her problems with self-esteem and stress for 3 years, but only recently have I mentioned to her that now I just feel like a roommate or an agony aunt. I've been pushed out of the relationship due to her own self centred nature (just to make it clear, for the first 2 years I never complained). It honestly just sounds like you broke him, and you should have known it. I can tell by what you've written that he has warned you a few times, but you chose not to take them seriously.
He said whenever he tries to have a serious conversation with me, I use self-deprecating humor that's not very funny as a defense mechanism.
Again, my partner does this too. And it is just a way of avoiding his complaints and turning them in on yourself instead of actually understanding how he's feeling.
Sorry if any of this came across as a rant. It isn't so much at you, but just being in a relationship that is exactly what you described, only on the other side. You honestly can't understand how frustraing it is. It sounds like he gave you a lot of chances (even if only one was an ultimatum) , and you didn't take them. And do you know how I read my girlfriend not taking up these chances? It just makes me feel as if she doesn't care enough about me to put an effort in to helping herself. And yet if I leave her I know she will fall apart just like you have.