I mean... his relatives are cowards too. They agree that his and his mother's behavior and attitude is bad and that it negatively impacted you, but they want you to go back to him? Nah. Maybe they like your work ethic around the store. Free labor. Yay.....
Sorry if that sounds cynical. Some families can be weird and ugly or develop hurtful dynamics. After my grandfather died my paternal side of the family went nuts and his two daughters attacked my mother who isn't even blood related. So please stay safe and don't give in.