Anyone know about filing taxes while separated? How much of a difference is there between filing alone vs. together?

Awesome Shark Lawyer says that it's best to file together this one last time before I can actually file for divorce. That we don't have to, but why cut off my nose to spite my face? We'll BOTH get a better return by filing together.

Asshole evidently went to the accountant today and tried to file on his own and the accountant told him we're better off filing together. And so he sent me a text saying that he doesn't want to file together because it will cause unnecessary stress, even though we don't even have to be together in the same room AT ALL to file together.

I think he has something in his finances he doesn't want me to see. I also think he's acting like a toddler who's throwing a tantrum because his favorite toy has been taken away.

But, bottom line, I'm not going to make a big deal about this if it's not really worth it. So, how much money can we really be talking about? What's really the difference, monetarily, between filing separately and together?

Thoughts?

I am SOOOOOOOOOOO ready to unshackle myself from this dumbass.