Kudos to your dad suggesting family therapy - he's trying his best to fix things, or at least that's how it comes over and he's not trying to blame you on anything, he wants the whole family to try together. Sounds fair and reasonable to me!

Just be honest when you go, the more honest you are, the more you will (hopefully) get out of it. I hope you all work things out and have a better relationship in the future :-)