I don't know what to do next, I feel like I can't just go away but at the same time I don't want to be here. Advice?

I'm so thankful I found this website, I've asked several questions here and I feel like this is the only place where people understand me and here I am again... In my last question I talked about our situation, me and my mom have been my grandma's only caregivers for 6 years ( she has dementia ), her two other kids don't care and we are at a breaking point, the situation is unbearable, my mother had a really serious heart attack two years ago, I'm mentally ill, there's no way we can take care of my grandma when we are extremelly sick as well. My grandmother now needs care 24/7, there are many sleepless nights and recently my mother started showing signs of all the stress that this situation causes. My mother rented an appartment for the two of us, her idea was to leave my grandma here in her own home and try to make her brother and sister come by more often and find a way to solve this solution TOGETHER, my mother is tired of doing everything by herself, she's not an only child. She called them to announce that we would be leaving by the beginning of August and that my grandma would be alone from then on, do you think they cared? No, they just said " You can go, we'll take care of it later. " It's been one week and a half since they last talked and not even a phone call or a visit to ask if grandma was already alone or not, I'm disgusted with their attitude. We haven't moved yet because there were some issues in my new room that are getting fixed but we will probably move in less than two weeks and I'm scared to leave my grandma here by herself. I thought about staying with my grandma but my mother told me I should go with her, that this wasn't my responsability, I somewhat agree with her and I don't want to stay here, I want to have the chance to start a new life but at the same time the guilt feelings won't leave me alone, I'm always thinking what if something happens to my grandma? I would always feel like it was my fault because I wasn't here... I already contacted the social services but so far no answer, my mother told me she will call them tomorrow, we will see. I just want a regular life like my cousins, they have their job, their own house, they travel, they meet people, I never had the chance to do any of that, I feel like I've wasted my youth and the worst thing is that my own family never recognized my efforts and I can see that they clearly don't care if I have a life or not, they just want a maid to spare them from all the hard work and problems.