<human>: Provide a brief overview of the text.

At first, I thought it was mid-life crisis until he threatened to kill himself over something really insignificant (my sister wouldn't pass a car on the road). 

Since then, I started to notice how he would throw tantrums at the smallest things like a small kid would normally do. It also seems like whenever I call him out for something, he'll outright deny it even though I was in the same room as him when he fucked something up (he didn't always do this). 

He never punishes my brother [18F], in fact, it seems like he thinks of my brother as his best friend and goes out of his way to defend my brother from my mom's [55F] punishment. As a side note, it doesn't seem like my dad has any friends, so he's either at home all day, shopping, or at work. 

I've tried taking him to a doctor since my sister thought something was wrong with his heart (I dunno, she could be right for all I know), but then he starts getting really aggressive about going, even for a routine checkup. I wouldn't know what to tell a doctor even if I did go to see one.
<bot>: My dad is acting more and more like a child and I don't know how to tell him or get him to a doctor.