Explaining myself

Why

I always feel like I'm never there for my friends. Like I feel like I can do something more to help them, but I just don't. I look at them when they need someone to help, and I try. But sometimes, I look at them, and I feel nothing. No sorrow, no sadness for them, no care. And I walk away, like nothing happened. It feels like I'm on this roller coaster of emotions. One day I feel happy and I'm talking with my friends and everything is normal. Then other days, it's like I don't even know them. And it's definitely not their fault, they don't even do anything to trigger this. And I'm sure it confuses the hell out of them. One day, I'm myself. Then another, I'm a bitch. I'm mean and rude and I say things that are hurtful. But they don't know that I'm not myself. So I'm just pushing them away and I can't do anything to stop it. I looked my friend in the eyes when she told me about something that was depressing her, and instead of trying to help her, and told her to "Just be happy, it's not that hard." I said this to her knowing what depression feels like, and what hurt feels like. But I had the audacity to say that to her. I cried that whole night because I couldn't apologize to her. I couldn't find the courage to say sorry after that. I don't know if I'll ever be able to apologize for that. But this happens all the time. I say things that I wouldn't normally say and they never leave my mind. I'm surprised they're still with me after the shit I put them through. But the biggest thing that scares me, is that I can't stop it or control it. What if one day, that's who I become? Cold and isolated. I don't want to be that person.