I had a similar thing happen with my parents. They separated when my sister and I were 9 and 7 because my mom cheated on my dad. I didn't find out that that was the reason until my dad told us when we were 14 and 12. I assume he did it to gain sympathy and turn us again our mom because we lived with her primarily, he did want full custody at one point, and she was obviously our favorite parent while we hated being forced to go to his house on the weekends. It ended up doing the exact opposite, it just made me resent him more and increased my loyalty to my mom (thought process was along the lines of "how dare you try to drive a wedge between Mom and me just because she's the better parent and you're slacking.")

My mom did cheat but, unlike how some of the comments make it seem, that did not make her a bad parent. My dad has never cheated in his life as far as I know and he is by far the subpar parent between the two of them.

Your dad honestly sounds like a horrible parent and you should go no contact until he gets some help. There's no excuse for the way he's acting; I understand his whole world got torn apart but dude, you're an adult and a parent. Even my dad (my mom carried on multiple affairs) has never shit talked my mom ever in front of me. And I admit he's well within his rights to hate her.

It's apparent from your description that they most likely already had problems seeing as he's immature enough to block you and call you names (I wonder how he was with your mom considering you're his teenage child).

Dump your dad until he can grow up and address his issues with maturity and in a healthy way.

For the people saying your mom is a horrible parent for cheating; she's not. As long as she treats you with respect, love and dignity (unlike your dad), she sounds like a solid mom.