Should I file separately if I just found out spouse didn't have any federal tax withholdings? Or am I liable for the debt either way?

Headed into divorce but not yet divorced nor legally separated. Just found out that husband's employer did not withhold ANY federal income taxes from his paychecks. I was unable to see his pay stubs and he didn't bother to look at them so he never noticed until *I* requested a pay stub (this year, for divorce purposes), and that's when I saw no federal taxes have been withheld this year. I asked why and asked him to check his stubs from last year (2022). Discovered no fed. taxes were withheld since he started the job last year. His W-4 is correct, so this was an employer error and I will report them. HOWEVER, he never bothered to check his pay stubs and gave me no reason to believe he was underpaying, especially considering both of us have always had *extra* withheld to ensure we don't owe at the end of the year (until this job. I had extra withheld in 2022, but his employer still withheld $0 federal.) I had no idea his payroll deposits to our bank account were "over" each week by the amount of taxes he should've paid and continued to use the full amount to pay our mortgage, utilities, child-related expenses, etc. His automatic payroll deposits were no higher than his previous job, so I didn't suspect anything was off. The problem? He significantly underpaid and I overpaid. I have not yet filed and am debating filing separately. Will the IRS still come after ME for debt that HE should have discovered and corrected within a few weeks of working there? (Shouldn't everyone go over their pay stubs when starting a new job?) Filing jointly, we'd get $100 refund. If I file separately, split mortgage interest, property taxes, and real estate taxes in half, and allow him to claim 2 of 5 kids (he's never home, has been cheating on me with 5+ women which was discovered by our 11yo child, is abusive but no proof of physical abuse because I was scared to report, is a compulsive liar, has major depressive disorder, was fired from that job mid-March, and is just an overall mess so I feel this is generous of me considering he does NOTHING for our home and just make it worse with holes in the walls and shoddy, 1/2-complete, DIY projects), he'd owe $6282 and I'd get a refund of $6202. We DO NOT live in a community property state. Advice PLEASE?? Am I liable for these taxes because they went into a joint account and were spent on our family's bills when I didn't even know it was money owed to the IRS? I don't think I'd qualify for Innocent Spouse Relief since I now know about the lack of taxes withheld and haven't filed or signed a joint return. Since I know about the error prior to filing, am I protected if I file separately? Will the IRS come after joint assets such as our home which hasn't yet been divided because divorce isn't finalized? I hope to finalize in 2023, but he's dragging it out by refusing to share info. (He also cashed out his 401k account this year to buy a new truck; he claims he works hard and should be able to drive whatever he wants...he's not even 50 years old! I am supposed to get 1/2 of that and he'll have to pay the penalties. We couldn't afford payments on a new vehicle so in his mind this was a good way to get a new truck (dumb!) and could do it without me because my name isn't on his 401k and he got a loan on his own. (My name isn't on the truck either.) Would they go after the truck first since it's solely HIS asset? He got a $10k bank loan, $10k cash gift from his dad, and borrowed $15k cash from his dad, (though I doubt he'll ever repay that), so the truck is "his" except for the $10k bank loan. If he continues making the payments on the bank loan he got, he'll own it outright by himself.) I'm scared, feeling alone, trying to protect our kids with sound financial decisions so we don't end up even worse off, and don't know the best (& legal!) way to handle this. Divorce lawyer suggested I eat the debt because it was put in a joint account & spent on our family, but I feel that's not fair. It hurts me financially when I paid extra federal all year to ensure a refund, and he's now hiding money in a separate bank account that I can't access, so I (and our kids) would be paying for HIS mistakes if the IRS comes after me for 1/2 or all of the taxes his employer failed to withhold when he's the one who didn't even bother to check his stubs and I had no access. (Yes, I need to find a better lawyer who will help me stand up for myself. It's crunch time though, and I'm in a panic.)