Wow. This is complicated and has a sniff of 'the script' about it.
It's entirely possible that from his point of view he couldnt sit with you while you cried for hours. Maybe he tried to hell but it was getting worse. You were sat in a car drinking a bottle of wine (where and how were you planning on getting home) and a colleague found you. Just a colleague. Not someone you were particularly close to? Not someone you had spent a lot of time with? Came out and happened to find you?
You are saying there was no lead up to this with the colleague, you didnt tell him where you were but he managed to find you, there was no in appropriateness to this?
Who had the kids? Your dp? Because if dp went out in the car sat drinking and texting s colleague to meet him then kissed them, it would be done.
It's really difficult to see if he wasnt supportive or if he was out of his depth. How many time did you disappear to sit a drink? I cant help wonder if, from his point of view, it was a situation like is seen on mn alot from a woman's point of view. Their husbands clearly have depression or a mental helathy issue, but it rules the family, the husband, wont seek help and expect everyone to pander to them and when they dont get what they want they disappear off. Often these men also have a drink problem (no idea if you do OP, but sitting in a car drinking a bottle of wine suggests it). These women are told they arent professionals and if the their husbands wont get help theres nothing they can do. The fact that you say its 'dramatic' and want him to accept he is a large part of why you cheated, suggests to me that you dont really understand what cheating does.
It's been 9 months. You have decided you want your family back. Maybe he does too but isnt sure wether he cab get passed or not. Its entirely possible he doesnt know what he wants. But has decided to not make a move until he does. That's sensible. Many people decide to try again after cheating and then a year or 2, down the line, they realise they cant move passed it.
I dont think he is trying to appear like the good guy by not finishing it. No one would cast him as the bad guy if he finished a relationship over cheating. So he already has that option.
Maybe he is stringing you along. The truth is, non of us know. But I have to say theres enough if this thread to make me think that you are massively minimising eha8ts gone on, on your part and shifting much of the blame to him.
You need to start being responsible for yourself and your own life. Which right now is probably to decide to move on. If you cant wait or if you think he is punishing you, move on.