WIBTA if I walk off a job

For context I live with my brother in law, and he runs a landscaping business. He seems to have gotten it in his head that because I live under his roof, anytime he needs help with his business I’m obligated to help him. On Friday he sent me a text message to make sure I’m free to work Monday. Now, I’m employed (I have a few of my own online businesses and a part time job on a regenerative farm) and I already had plans Monday (today). It makes me feel like a pushover, but to try and avoid drama and an argument with the person whose house I’m staying in I just moved my schedule around. So, I’m already pissed off at the situation so then Monday comes, wakes me up at 4:45 am. Get in the car to leave to the job site (or so I think) at 5:30. We roll up to a building, he says to chill out for awhile and he and my nephew get out and go on. Tell me why I look at Google Maps and we’re a jiu-jitsu studio. I got woken up at 4:45 on the morning to wait in the car while they go to jiu-jitsu before we go do whatever job he thinks he’s entitled to my help with today. WIBTA if I just walked off while they were still in jiu-jitsu? I know this will cause problems, and put my housing at risk but I feel so disrespected right now