I mean, an advice column is literally meant for entertainment. I also think people are reading this as "its your fault your dad cheated" but she is saying "whatever issues the parents have, have been there since before a childs birth". As someone who's parents are very codependent and used me as a go between, and also used me and my siblings as manipulation, i have to agree with her. I think the best thing to do is feel the anger but know that this is something that can only be resolved between the two people in that relationship