Partner's mood swings are affecting me and my quality of life

I've been with my partner for 12 years and in recent years, he's developed some intense mood swings. He's never physically hurt me but the way he talks to our child (10m), and I is unacceptable. I'm trying to understand what is "normal" or abuse. He's checked his testosterone and it's pretty low--he's only 33.

I realize part of this could be the testosterone, but he doesn't apologize for his language or take accountability, he believes it's normal. Examples: to our son, "take a f-ing shower" "pick up your f-ing shoes" "how many f-ing times do I need to repeat myself?", etc. To me: "f this sh**" "can you stop making those annoying f-ing comments" "f you too" (if I stand up for myself). He'll also be happy then by afternoon go non-verbal and want to be left alone.

I'm at my wits end. I've talked to him numerous times about this behavior, and he doesn't care to change. At what point do you draw the line between mental illness and abuse. We are on a never-ending cycle of these mood swings. I love him and want the best for him and us but can't go on much longer. If you have dealt with a similar situation, please reach out. I am confused.