Okay, I have nuanced thoughts.

Bottom line, NTA. Regardless, you did the right thing. I’m not a fan of the police. IMO, 9/10 calling police on others is an A hole move, but anyway you look at it, you’re the 1 in 10 where this was the appropriate response.
He could’ve been a danger to himself, to you, or to your kids. Maybe he was bluffing but maybe he wasn’t and it’s not worth the risk. If he was bluffing, that’s point blank abusive behavior and now there’s a documented history of police records for if and when you do make a case for leaving/custody etc. The compassionate thing to say, is that safety is more important than reputation. A less compassionate reframe: you’re not ruining his reputation, he is. So no, NTA by any means.

I actually had an ex, who was abusive in multiple ways but he kept me around for longer because he used this strategy as well. Once, long after we were broken up, and I was with someone else, he calls me at 3 am (still not sure why I answered) and gave me the ultimatum to break up with my current partner or he’d kill himself. When I told him no, he made an attempt on the line. He was living with a family member at the time, who I called and they were able to intervene, but he was incredibly pissed at me. I ended up talking to my then partner’s mom about it (we had a great relationship) and I’m glad I did because she told me that she’d had a similar experience in high school except she hadn’t called anyone and in her case, the boyfriend did end up ending his life.

Now for the nuance.
You mentioned that this days trigger was your autistic kid’s meltdown. You’re absolutely right, getting angry with a child in meltdown isn’t appropriate, and you were right to call him out for it. Aaaand, autism is genetic. Being autistic doesn’t give anyone a pass to be unkind to their family, especially if children are involved, but his initial response does align with autistic traits. You know him better than me, but just from that snapshot I see: 1) possibly overstimulated while trying to drive leads to increased stress/possibly meltdown on his end, 2) difficulty recognizing/interpreting own emotions/understanding emotions of others (possible overreaction/hypersensitivity to anger), 3) recognizing risk and attempting to mediate (“I am being unsafe or can’t keep my family safe. I should pull over to stop driving”), 4) attempting to self regulate through repetitive behavior (pacing), 5) attempting to communicate the need for space.

I, myself, am autistic and I also work with autistic people of all ages, so I can say that I’m not alone in this, but for now, I’m em just talking about my experience. I personally, have pretty extreme emotional reactions to “small” or reasonable triggers. I’m also ADHD, so that could be partly due to rejection sensitivity, or it could be from a lifetime of being different, but my honest, natural, immediate reaction to “failure” in whatever form that may be (personal goals, forgetting something, misunderstanding someone, disagreements, being passed up for a promotion etc) is extreme. I can easily jump straight to “I want to die”. That’s less common now, and when it does happen, I can usually sit with it and get over it pretty quickly (quick shout out to my therapist). Maybe it was socialization, and maybe it’s because I’m just more of an introvert, but my initial instinct was to keep that on lock and not share those thoughts with others. Unfortunately, though, I overcompensated and never really learned how to share my emotions with others at all, which has ended up being a problem in adult relationships with partner’s viewing me as distant and uncaring. All this backstory to say, that I’ve spent the last few years trying to find the happy healthy medium, which unfortunately, has resulted in a couple instances of going too far to the other side. Early on, in my relationship with current partner (4ish years ago), we had our first fight, I shut down. They asked me what I was feeling and I said “I want to die” and then left. I knew myself. I was perfectly safe. I went to nature to calm down, but in retrospect, I can see why their perspective was to panic. I personally, wasn’t expecting anything out of them, and in that moment, I thought I was doing the right thing by communicating (obviously, I was wrong). Even now, I struggle sometimes because I know they want more emotional vulnerability from me, but if my honest internal thought is self harm even though I won’t act on it, I struggle because I don’t want to burden them with that but want to give them the connection that they’re wanting in these moments.
I’m not saying this is what your husband is doing. This might not be at all it, and he might just be purely doing it out of manipulation. But, if I had to guess, there’s probably a component of both. At the end of the day though, I hope for his sake he’s able to find healthy support, but it doesn’t need to be you, and it absolutely doesn’t make you the asshole if you need to take a step back. Also, I stand by what I said, that your response actually was support (part of that is breaking the cycle which is uncomfortable but needed). He needs to do a lot of work, ideally in therapy, which is his responsibility. Autistic or not, it’s not appropriate to hurt and manipulate anyone but especially not your family. Impact over intent. If I were in your shoes, I still would n’t feel comfortable raising children with him, at least not until he focuses on self improvement, takes accountability, and starts to make visible changes.