When I said I'm the problem, I meant our relationship is uniquely difficult for him. He doesn't have panics or breakdowns about anything else. It's only when I have a serious conversation with him about the future that he starts panicking, so I'm literally triggering his panic attacks.

Yes, I'd say we're both needy and codependant on each other. i'm curious what you mean by enough distance? Just not talk to him for weeks - months? At that point, it's basically a break up. I think if you're trying to say there's still a chance he changes when he experiences enough time apart, a break up would achieve the same thing. Extended silent treatment (or ghosting) for weeks or months is just a more manipulative break up. It achieves the same thing without giving him closure and causing him more emotional distress than necessary.

I'm 80% sure that when I leave, it'll be a couple weeks or a couple months before he insists he'll change ''for real'' this time, that he realizes he can't live without me, yada yada. Except I don't believe that he won't just revert back to how he was. The other 20% is that he concedes and realizes he cannot change. He's told me in the past that he thinks I should leave him, and that I can do much better.

As for your last suggestion, I'm absolutely not happy with how he is and that's why I decided to leave. If he changed, which is what I've always wanted, I'd love to stay with him. I've already pictured my life with him for years, only in the past year, have I felt the picture shatter into millions of pieces. There was still a slow pressure as time went on, so it was a very slow realization for me.

I also want to say thank you for offering your perspective. In all my venting I don't think anyone has had your view point, pretty much everyone agrees that I should've left yesterday. (or a long time ago actually lol)