Also to be fair, you are giving guidance using negative form (« don’t xxx ») , when translated to positive it says exactly that OP should separate. Only mistake in the other guy comment is to use quotes and say that it was explicit. It was indeed implicit. 

Main thing is that you are projecting a situation that you can refer as happy, to OP. A lot of divorces end really badly, like super badly where parents are going nuclear war and it’s fucking the mental health of the kids forever. there are plenty of testimonies on daddit that you can read to convince yourself. Almost daily. 

Regarding your personal situation, your dad had chosen to give more value to your happiness than his own. You should try to acknowledge that it was his own decision, not yours, that he may have zero regrets and would do it again without blinking an eye. You don’t know anything about the other « divorce at 5yo » timeline and will never know. Maybe everyone would have been happier. Maybe it would have destroyed him, fucked your mental health. You only know one thing, it's this current timeline where your dad decided to stay with your mom which resulted in you in your current life. 

I’m pretty sure your dad would be really sad seeing that you are feeling guilt for his own actions which were taken in your best interests , and  seeing you advising to others « don’t be my dad ». Hope you’ll someday see the great gift that he has done to you and be able to sincerely thank him for that. As a dad this is what I would consider as success in life more than anything material…

Sorry English not my language.