Should i tell my mum about my cheating dad?

They’re married for over 20 years now and i’ve noticed since young that my dad cheats on my mum. I know for a fact that my mum knows too but she won’t leave him. i’ve seen the tinder app on his phone he’s had it for 3-4 years now

i think and on the bluetooth devices in my mums car there’s another women’s name “Sarah’s iPhone” and ik it isn’t my mums friend she hasn’t got friends called sarah and neither does her friends get in her car. My dad has been using my mums car for the past year so it’s got to be him. Please tell me how i can approach this to my mum.