No problems, and I'm sorry if I seem extra harsh or focused on you. My main reason I'm focusing on you is because you're the only one in control of your own actions and before you can deal with any other relationships you have to deal with your own relationship to yourself. It will also make it easier once you've developed self confidence and assertion to ascertain if he really is emotionally abusive or not.
when he's blaming me for stuff, I do call it out at the time, it falls on deaf ears/makes no difference, but when he's not upset later and I bring it up again, then he often apologizes (not always though)
If you call it out and he is still blaming you, you need to straight up leave. Tell him "I'm giving you space but I refuse to be blamed for this, I'll let you calm down, and I expect an apology." Then withdraw and give him space. It sounds like he's a bit mean when he's mad and likes to point fingers, but when he's calmer he realizes he was wrong. It could also be that he feels just in his anger. You need to be firm that it's not your fault and never accept fault when there is none.
how he shows his bad mood in public: glaring at me, talking to me rudely
If he's being that way then do your own thing or talk to someone else. Refuse to engage in the childish behavior. You shouldn't try to mitigate him when he's acting like a baby. And you should tell him "you're acting passive aggressive and it's ridiculous. I'm not going to coddle you when I've done nothing wrong." And there's nothing wrong with these statements at all.
eg if it's time to start a class I'm teaching and he's a student in, he just won't do what I'm asking the class to do, making it obvious that he's upset (this crosses over with the sabotaging work point, he doesn't always come to my classes but if he does come to one, he doesn't treat it like he'd treat a stranger's class if he's upset)
If he doesn't do what you're asking the class to do then kick him out or give him a bad grade. Seriously. Don't tolerate this behavior. I'd honestly even suggest that you tell him to find another teacher as there's clearly ethical reasons. In the same way that doctors do not perform on their partners, you shouldn't be teaching your partner.
He withdraws with the expectation that I will come and fix things.
I mean, can you blame him? For the past ten years you do come and fix things. This isn't going to take overnight to fix and it's something that in part has been contributed to by you. Stop fixing things. Either he'll get over it or he won't (which is a future problem that you can deal with) but you're not going to be there to take responsibility for him anymore. Decide this now.
A couple of times when I've tried to just leave him be, he's gotten more upset and escalated and that's when he's broken stuff
That's when you need to get out of that situation. This absolutely is abusive and manipulative behavior right there and you shouldn't tolerate it. If you feel genuinely afraid then call the police. This is intimidation and unacceptable. I'd also be very open about this with family/friends and any other support you have, as this should never happen. He should feel ashamed for this and you should never apologize or tolerate him acting this way.
It's not always the thing he's looking for an apology for, but it's definitely with the aim of appeasing him and calming him down.
Start apologizing less. You should never apologize for how he feels because you have zero control over how he feels. "Sorry you feel this way for what I said" should never happen, ever. The only thing you should apologize over are things you said. Do you genuinely regret what you said or think it was intentionally malicious? No? Then don't apologize for it. If he takes something the wrong way that's on him. Again, no coddling, even though you might have the urge to. "I didn't mean to upset you, I said this because of (y)" is a better response. But no apologizing if it was something you said without being malicious.
He was saying she shouldn't have been singing when she was cos he didn't want to hear it (we were in a car and he doesn't like people singing loudly in cars).
I don't like people singing in cars either. I don't blame him for saying it at all. Is it kind of rude, sure, but he wasn't out of line for saying it.
Then I said "but she's a good singer, right, even if you don't want her to sing right now?"
That's beside the point and you should have never interjected this at all, ever. That's literally asking for problems. Again, his relationship with her and his actions are completely separate and not your responsibility. It's kind of like seeing a fight and then jumping in the middle to defend the two people fighting. It's just going to end with people mad at you and you getting punched in the face. There's no reason to interject and it is detrimental.
I said again "but maybe it's not a bad time to affirm that she's still a good singer" and he just repeated "she shouldn't sing in the car"
It was a bad time because it had nothing to do with her singing ability and implying that it did adds more insult to injury. He literally just didn't want her to sing in the car and he's entitled to that. It's annoying. If she was singing at an appropriate place that'd be rude, but in the car is not nice. I'm completely on his side in this example, and again this is a PRIMARY example of how your conflict avoidance and desire to be the peacemaker just exemplifies the issue massively.
She was also a relatively new friend at the time, not an old friend who could put up with it cos of old friendship and deep love etc.
It's not like he was trying to hurt her. It's that car singing annoyed him and he's the type of person to stand up for himself and his opinions. Honestly, why did you care that he stopped it? Did you particularly want her to sing? Did you ask her to sing? People singing in a closed space, regardless of their ability, is annoying to the vast majority of people, and rude to subject other people to. In fact, I encourage you to be MORE like your husband in this area. Find something that annoys/upsets you and tell someone to stop. I guarantee you'll find that things go a lot more your way.
For example, I was just on a trip to Madrid with a friend. She has a habit of being really pushy and TBH I was completely upset with how she behaved, but I stood my ground and made it well. I funded the train tickets to and from Madrid. She gets on the train and sits immediately at the window seat. I said, no, I want the window seat. She moved. I could have sat there and festered out of "politeness" but why should I? It was rude of her to take it in the first place.
She's also vegetarian morally and I've got IBS, lactose intolerance, and a sensitive stomach. She wanted to try a vegetarian restaurant that was mostly greasy. I told her no the previous night before the trip because it is too greasy. While there she tried to get me to go and I again put my foot down and said absolutely not and it is a matter of my health and I told her I already researched vegetarian restaurants in the area and we'll go to one of those, period. Putting your foot down/being assertive about your needs and wants is healthy and important. I was not going to go to somewhere I knew would make me sick just to appease her, when tbh in the reverse situation she wouldn't (and shouldn't) do the same.
And when we got there, she grabbed the menu and read it, and then when I finally got it (it's huge so one per table) the waiter came over and asked if we were ready. She said yes and listed her food. I told him nope, not ready, still reading it and he gave her a look and said for her to wait until we're both ready. I then was like 'um, are you serious?" and while she ignored the remark and looked down, it was important for me to call out that bad behavior because that's self respect, you know?
There's a lot more examples of that trip (she was unfortunately extremely rude and I genuinely don't think it was malicious but rather just a bit of self-centeredness) but I think you get my point. You should not just appease people, you need to stand up for yourself and stay out of fights that you have no dog in, you know? You should have never gotten involved when it came to him/your friend and honestly it sounds like you interjecting made it worse. If he's an ass, let him be an ass and watch him fall on his face. Don't defend him or try to cover up for his mistakes, especially if he is unremorseful.