You are not a sociopath. You clearly feel a lot of emotions, and even if sometimes you feel numb, it's normal. Sometimes, it happens because you feel a lot of different things all at once, and even if you spend hours crying or being angry about it, your feelings don't go away, but you're just used to having them. I know that for me, I can reach moments when whatever made me cry can't make me shed a tear anymore, and it's not because I'm over it or because I don't care anymore, it's just because I've spend so much energy into that one thing that I'm too tired to do more. And it's okay. It doesn't make us any less human. We're just tired. And I assume you've had these feelings for a while now, so it's OK to feel numb sometimes. You're just tired of all this.

And no one likes to be yelled at. Especially by someone like your mother. And I can't imagine what that's like, but I've been in a similar situation, and luckily you have your brother with you who knows exactly how you feel. Don't ever forget he's there for you, just like you are for him. It's not easy coming home to an environment like this, but try maybe having a calm discussion between the 3 of you. Even if she begins to scream, try to have a clear discussion, just to say that her yelling has really affected you, that you now dread her. But if you do talk to her, stay as calm as possible, and express as well as you can your feelings about the situation.

I feel like you may have a hard time trusting people, which I understand. But remember it takes time to build trust, and it also works that way for you. When there's a lack of trust between two people, there can be a lot more tension that builds up. Hearing what happens with your girlfriend's friend, I understand that it's hard to know who to trust. You do have to be vigilant, but don't let yourself build a wall around yourself, or you'll feel even lonelier.

I hope this helps you a little bit, I'm not really a psychologist or anything of the sort, but I try to speak from my experience, and I hope you can learn from it.

And I'm sorry to hear about your grandmother. Even if she's gone, she'll always be in your memories, and no one can take that from you.