Am I wrong?

My parents split last June very abruptly. They decided to throw me in the middle and call me every single day to bad mouth the other. I’m 26 and they’ve done this my entire life; throw me in the middle. I eventually quit talking to both of them because I just could handle the negativity they were pouring into my life. A few months went by and I opened up the line of communication with both of them. Thinking surely they’ve calmed down some. Not my dad. He was calling me 15 times a day. Texting me probably 50 times a day with nothing but negativity. I asked him to please stop, as I didn’t need to be his outlet for his problems. Parents should NEVER involve their children in their problems in my opinion. He ignored me asking him to stop, kept calling me numerous times in a day. If I didn’t answer he’d leave a 5 minute voicemail each time. He’d text me over and over in the middle of the night. He just refused to stop. So once again, I cut off communication. Yesterday, I reached out AGAIN thinking he’d get the point and quit acting the way he was. Nope. He immediately went back to the same behavior. I told him I was not ready to speak to him because of his behavior and I will let him know when I am ready. He ignored me completely and changed the subject. It’s almost as if he’s lost his mind. He just doesn’t get it. What am I supposed to do?