Is AUTHOR wrong in the post ? POST : TL:DR- SO works 3rd shift and takes care of LO during day. Lack of sleep has taken a toll on their mental health.

Backstory: SO and I have under 1 yr old child. Daycare is expensive. I work 1st shift (630-230p). They work 3rd shift (10-6a). Our bulidings are close enough for baby trade off in mornings. SO watches baby during day, naptime between 9-12p. I take over baby duty when I get home at 3, SO sleeps till 7

SO has been struggling with getting enough sleep since I came back from leave. I am very concerned for their wellbeing and safety driving hi-low at work. I made some suggestions to help:

There was an job opportunity at my ideal workplace, position would be Fri-Tues 8a-5p. SO vetoed this because then I lose vacation time and forced to get my own insurance.

My retired parents could watch him a few times a week. They live 45mins away but we could meet halfway for trade off. Aside from gas money, care would be free. SO does not like in-laws since they felt I could have done better and told them such while we were dating. My parents respect my decision marrying and are civil towards SO.

The lack of sleep and general stress has gotten to SO. Angers quick and much more snarky towards me. Easily can get frustrated with LO. When well rested, I get to see that loving supportive person again.

I have no longer the option to change jobs; I need the time off for relatives passing away after the holidays. I can't change my shift; its dumb luck I got to 1st and we plan for me to go back to school in evenings. My future degree will allow SO stay home. 

Our mutual friends have noticed the changes in SO as well; its not just my mind jumping into stuff. 

If I mention about being sore or tired it becomes a game of one-up to SO. I have been accused of cheating, not helping, and delayed PPD. I stand there and take it, knowing its the lack of sleep. But I am getting to my breaking point. So....

WIBTA on giving the ultimatum to SO: Leave third shift or I am leaving.