Am I being a jerk?

Becca

My boyfriend and I had plans to go to our couple friends house and have had these plans a month and half now (they live super far) and he just recently moved in with his parents to save for a couple months until we get a place. His mom said to him tonight “you better have Saturday free, because we need you to fix our lake house dock that got destroyed.” And he told me like I wasn’t going to be upset, so I responded “no, we are going to our friends, we’ve had commitment to go for a month and a half now” and now he’s like “I don’t know what to do now” but isn’t it obvious to tell his freaking mom to either A. Hire someone

Or B. Wait till the following weekend when he doesn’t have plans. Might I add in that we are in a long distance, and my only time to see him is on weekends. Tell me what you would do because I need help😩 I just want to explode on him for not speaking up about plans, or his mom about just assuming he can just drop everything to do this for her.