How do I do this?

So since my baby was born 4 months ago, it’s been one shitshow after another. My wife has been severely poorly and needed me on constant call. Thankfully, I’ve managed to be off work in that time so I’ve managed to catch up on sleep I’ve missed during the day (at least getting me to a semi-functional state).

However, I can’t have anymore time off, now. I have to go back, or I risk losing too much money for us to afford.

Today was my second day back, and I am just so shattered. I’m getting a maximum of 4 hours sleep a night which was manageable while I was off as I was able to get a boost of a couple of hours during the day. Now, I can’t have that. Last night, I managed 2 hours of sleep and I feel so tired.

I don’t know what to do. How can I continue this? I know my wife is probably feeling the same but just isn’t fussing as much as me (which makes me feel guilty!)