And in the conversation if he tries to bite back about not being able to afford to move out... where do I go with that? Because I know that's going to come. I was thinking of H, this is a decision you wanted. It is not in my best interest or the boys to be here with you coming late at night and being disrespectful with your involvement with other women while remaining in our family home --- and end it there.
Why do you even have to talk to him? Why do you have to defend your choice to file?
You do not owe him an explanation. It seems crazy to me that you're prepping your detailed explanations to defend a very rational choice.
If he couldn't afford his own place, it looks like he didn't think this through very well. That's on him. It is not your problem.
T, he left because everything was your fault. You're right that filing for D means everything will be your fault. It's up to you if you spend any of you brainpower giving validity to his claims, such that you need to defend yourself to the man who left you when you had a newborn.