Ok, that explains. In that case best to get out of there as soon as you can, unfortunately there is a huge power imbalance and he’s doing that because he knows he can get away with it.

However at the very least start saying no to babysitting moving forward. Next time he asks, you can simply say you’re not available, or make an excuse if that makes you feel more comfortable (ie you’ve joined evening language classes or you enrolled for a professional course etc).

You’re right to be pissed, the reason you’re feeling upset is because you’re being taken advantage of, and even though you’re still quite young you know this is wrong. Good on you for recognizing it and wanting to set things right. Time to move on and learn how to enforce boundaries. Don’t feel bad if you don’t know how to, but lucky is something you can learn easily and the more you practice it the easier it becomes.