Hey there, wondered if you could wait out another six months? That way you can file for 'two years separation'. The biggest plus of this approach is that it is 'no fault'.
If you want to file before that time, you have to file either for adultery (not so easy to prove) or Unreasonable Behaviour. The latter two are obviously a 'fault' based divorce, so if it's likely to lead to worse behaviour from your TBXH then you might want to think about the 2 years as an option.
Can you text him to say you would like to talk about the future, and make an arrangement to phone him/email him so that he is given advanced warning that a difficult conversation is required.
You could start by saying that you are comfortable now that you've established a new routine with each other and the children, stress you don't want to change that, but you feel that you should now formalise the breakdown in your relationship. It doesn't mean anything has to change, but you could offer him the opportunity to divorce you for UB if he wanted,
And I know what you're thinking: But I'm not the unreasonable one.
It doesn't matter. You can be 'unreasonable' for not being an alcoholic!
or just ask him if he would give consent to '2 years separation' divorce approach in six months time.
This way, he feels like he's in control and making the decisions.
Try to focus on the advantages to him if you can, not your reasons for wanting a divorce (if he's a control freak). Make a commitment to him to be as agreeable as possible (e.g. no legal letters, no threats of 'taking him to the cleaners', if you're happy with arrangements now etc).
The key thing is that he might not like you making such a big decision, but if he gets legal advice, almost certainly he will be told 'try to do everything to keep the other party calm and agreeable'. He will definitely be told he cannot prevent you divorcing him so the sooner he comes to accept that, the better.
Whether or not he takes that advice is down to him. However, if he decides to get difficult, do remember that you do have recourse to the CSA (I know it's renamed now) and also to an UB divorce approach yourself.
Usually given time to calm down, people do and want to avoid having more stress in their lives so give him a bit of space to do this.
I imagine it is a very difficult conversation to have, but it's going to be difficult regardless of whether you have it this week, this month or in the next century. Be prepared for some reaction, but don't lose sight of the goal you have set.