Hi op.
we had a daughter who found her teens very difficult.
things that helped us:
me and my then husband had a meeting each week to agree strategy. So if we agreed that we weren’t going to nag about the bedroom that week we didn’t
we disagreed on quite a lot of stuff but the agreement we came to was that we would back each other up if we’d agreed on something in advance.
if I unilaterally decided to have a go at her about her room and we hadn’t agreed on what to say about it he didn’t have to back me up.
honestly it did help. Not so much with our daughter (she was diagnosed with an auto-immune disease which causes fatigue and cognitive problems) but with us feeling like we were on the same page.
a diagnosis helped aswell as then we could both have some confidence in the future.
like your situation, my dd and my husband often clashed. He got angry very quickly mostly I suspect because deep down he was worried about her future and was trying to get her to be “normal” and do chores and go to school.
they had some spectacular rows, particularly as my dd really did have a temper on her in those days (she has much better control now) and she’d respond by saying things like I never asked to be ill and I’m just too tired etc etc.
if your teen is getting anxious and missing school and is having issues I would genuinely recommend (if your husband comes back) that you and your husband sit down and try to agree some boundaries/rules but also look into what else may be going on - get gp to check for glandular fever, speak to your dd about anxiety etc.
eventually my dd and my husband had a spectacular row and he lost control and hurt her quite badly, so we had to leave as he was violent and out of control.
i’d like to say he regrets it but I’m not sure. My DD has several diagnoses now of mostly auto immune stuff and uses a wheelchair as she has a lot of trouble with fatigue. I think he still believes he could punish her out of her illnesses.