I'm not a divorce advocate either. But yes, the damage getting done needs to be weighed. Everyone's situation is different. For me, living with it I think did more damage than good. But if you think this is just a phase, well, that is something to consider.
Do you have open dialogue with your kids about how their father's behavior is affecting them? They seem to mention it in comments, not directly, but I can guarantee you that they are aware of everything. They may not want to mention anything to hurt you or their dad. My dad never spoke about my mother's absence while she was physically present.
When your S said "dad is in his room 99% of the time" did you open up that dialogue? When my mom hid away 99% of the time, it tore me up. I wish someone had asked me how that made me feel and really explained what was going on. I only understood as an adult when my dad finally explained it to me. he was always afraid of bad mouthing her, but there was so many things I didn't understand and I just made assumptions about.
I am not saying run out and get a D. There may be a point this phase isn't just a phase anymore and you may find you are done. But I really don't think staying for the boys ever will really be staying for the boys, because if a time that comes where you don't want to take it anymore, I am sure they don't want to take it either.
I do pray he snaps out of it and sees what a beautiful family he has right before him.
