tired of being his family's chauffeur

I've been with my SO for 4 months but known him and his family for going on three years. I love his family deeply. My SO doesn't have car insurance currently so I come to his house to see him. It sucks but I don't mind. What I do mind is that it is thanksgiving day. We've been using my car this whole time, please keep that in mind. We had to go to his house this morning to get him some clothes for my family's thanksgiving. His mom informs us we have to go bring his cousin,
Who is 30 minutes away, some stupid truck ramps. We got to my thanksgiving at 10:48. It was a one hour drive from bringing the ramps to his cousin. We had to leave to go to his at 12:30. I missed out on my family traditions because of his cousin. We didn't even eat dinner with my family Now we've been at his thanksgiving since 2 and it's now 5 and we are having to drive his dad and little brother to Walmart which is 25 minutes away, then go pick up his friend who is 45 minutes away from Walmart, then bring him to his dads house which is another 30 minutes then drive to wonder which is 25 minutes away. And through all this, we were only going to be at his thanksgiving for an hour.