<human>: Can you provide a brief rundown of the text in within 3 sentences?

My mum and stepmum are obviously very sad. Frankly, I don't know why my dad could do this, and how he was able to keep this secret for two years. He didn't even marry that 21 yo girl. He bought her a car, expensive watches and bags, and we just discovered that whenever he said that he had some work out of the city, he actually drove that girl traveling around - to beaches, hotels.

I'm pissed. He didn't even bring us his wives and children around to anywhere. I was the one who drive my mums and siblings to every single thing. Knowing that sometimes my mum and auntie had to fork out their own money for us while my dad can bought that girl a car and everything really pissed me more.

He is approaching 50 very soon and still living like he's 25. I'm already 24 and I can't imagine myself having a 21-year-old stepmother and call her 'Auntie'.

Now that the truth is out, my mums are currently very heartbroken and both asked for divorce (fasakh?) if my dad doesn't stop seeing that girl. My dad somehow agreed ( I don't know frankly - He lied so often so I doubt we will believe him anymore.). Now the girl contacted my mums, insulting them, called my stepmum ( my dad's second wife) and said that " you are also a husband-stealer' and 'I will win'. She threatened to expose my dad's infidelity to his boss if he won't marry her because he should be responsible for what he had done.

There's something really twisted with how the dad can't get enough with two wives and the son (me) is a 5-year-monogamous closeted gay dude.

I'm the eldest son. My moms practically begged me to talk with my dad about this because now my dad refuses to do anything. I guess he's just lost. Karma strikes back. The thing is, I don't know what to say to him. What would you do if you were me?
<bot>: Clueless 24-year-old eldest son asked by moms to slow talk with 50-year-old dad about his 2-year infidelity with a now 21-year-old girl. What to say?