Do you believe the buyer is responsible, the seller is responsible, or it should the $300 cost be split?

I sold a car to a guy for $5350. The car was sold as-is with a transferable extended warranty. He saw the car on a Saturday about 6pm. He gave me a $100 deposit and we agreed to meet at the tag agency on Monday morning at 9:30am. The car had no license plate (the plate was previously transferred to a newly purchased car) and so couldn't be driven out of my development. On Sunday, the buyer said he can't make it at 9:30am, so we decided to meet at 11:15am. I had another meeting soon after that, so I had to go directly from the tag agency to the meeting. We met at 11:15am at the tag agency so he could get a tag for the car. I gave him the keys, manual, warranty information, and signed the title over. He was going to pick up the car from my house and put the new license plate on so he can drive it off. He gave me part of the cash and said he would give me the remaining $3000 that night after he picked the car up (he signed a paper showing the remaining cash owed). I went to the meeting. A few hours later, I received a call from him saying that he's at my house and the back window of the car is cracked in. I was finished with the meeting and said I could probably be back home in about 45 minutes. He decided not to wait and to take the car home. That night, he told me that he got the back window replaced and we can meet the next day so he can pay me the balance. When we met the next day, he wanted me to sign a document that said he only had to pay $2550 of the $3000 balance with me paying him $300 to replace the back window, $50 to detail the car, and $100 he would hold until I paid the $40 to have the extended warranty transferred into his name. I did not sign the paper, and he started yelling saying he wasn't going to give me any of the $3000 balance, and that I can try to get it in court. I had brought a spare tire for the car which I found in my garage and gave it to him a gesture of goodwill. He calmed down and gave me $2550 and said he would give me $100 more once I set up the transfer of warranty. I offered to split the transfer of warranty cost of $40 (even though I had no responsibility to since it wasn't in the contract). I said I wasn't paying to have the car detailed, which he eventually agreed. I also said that while I do not think that I was responsible for the back window, I would split the $300 cost so we can get everything done. He said no and that he wants me to pay the full $300, non-negotiable. My opinion is that neither of us know what happened to the window or when it happened. It may have happened when I still had title of the car or it may have happened after the buyer had title of the car. The only thing we know for sure is that when the damage was discovered, the buyer had title of the car, and so I think he is responsible. Plus, he never showed me pictures of the cracked window or any estimates or receipts to fix it. As far as I know, he might just be making this whole thing up as a way to lower the price that he has to pay for the car. In order to avoid this thing escalating and going to court, I then offered to pay for about 75% of the window repair. He refused saying he wasn't responsible for the broken window and that he is not paying any of the $300. Do you believe the buyer is responsible, the seller is responsible, or it should the $300 cost be split in some way?