You obviously still want him back, there ain't no 'sort of' about it. Be real! You want him back! It's okay!
Right, now that we've established that...
If you send him that message, all you will be doing is making him responsible for your feelings. Guys hate that. PEOPLE hate that. What he would be hearing is 'I can't deal with my problems so I'm going to blame them all on you, you should feel bad, you should be the White Knight, I don't have the discipline to sort out my own things, if you don't take me back then you're a bad person.... wrapped up in romantic rhetoric.'
If you loved each other so much then it should be a given that you're upset by the breakup. You don't need to rub how upset you are about it in his face. All you're doing in that message is vommitting all over him with your confusing, ambiguous feelings. What is he supposed to do with that information? What are you trying to get from this? Not closure. If you wanted closure, you'd give it to yourself right now, turn the page, close the book, not contact him again until and unless you ever feel ready. After all, I'm sure you've got your own friends, why would you need to add an ex to the list? You're not obliged to keep him in your life just because you were together once upon a time.
Nah, you don't want closure. You want to get him back, in two ways: you want him to feel guilty about whatever his part was in the breakup/the things you didn't like, so 'getting him back' in the vengeful sense. Yet you also want him back as in, you want him to be your boyfriend again. Oh the inner conflict!
Here's what you want to happen: you want him to say, in response to that message:
'Sweetheart I've been a fool. You're right. Niether of us were perfect, but I hurt you bad and I understand that now. It was silly of me to throw us away so easily. I've missed you. When I get back, let's meet up and talk. No pressure. But I think it's sensible to meet up and talk about this in person. Perhaps we can move past all this.'
Is that not the outcome you want? You want him to, firstly, RECOGNISE whatever it is you blame him for, THEN you want him to want you back. You don't want him to simply come back and be as he was. You want some things about him to change, and I guess you were hoping that leaving him would make him 'think twice' and realise what he'd lost etc etc. That hasn't happened, so now you're upping the pressure.
Look, I think you need to decide exactly which side of the coin you're going to follow through with. EITHER you want him back hands down, no ifs, no buts, just want to be with him again full stop. OR you can decide that, actually, you CAN get over it, it WASN'T good enough for you, and therefore you DO, genuinely, want closure, with NO ulterior motive of making him feel bad/guilt-tripping him into wanting to be with you again.
I know you really want him to see how bad this pain hurts. But it's not his problem unfortunately. It's over now. He can'y hold your hand through the breakup too. So!
If you decide that you do simply want him back and that's it, then your best bet, if you're going to message him, is to be totally honest about it. Say that you want to give things another shot, address whatever happened between you that caused the breakup, and honestly, maturely state the bits where YOU were wrong. Don't blame him or make him responsible for your feelings. Just be totally honest, even if that makes you vulnerable, he's worth the risk, right?
OR... if you DO, genuinely want closure... then just walk away. That's all you have to do. Just do nothing, give yourself the gift of closure.
Because I promise you, spamming him with that pile of emotional pressure is just gonna make him move away more, react defensively, and probably say something that will upset you. So your current approach isn't going to get you anywhere.
You were with this guy for 2 years. Surely that's long enough for you to not need to play games/have tactics/be ambiguous. You either want him back or you don't. Act accordingly. And don't try to change him.