Down and out, in need of some help

I’m brand new to this site, but I figured someone would be able to give me some advice. I don’t know what to do. I feel helpless and hopeless to this depression, this feeling. I’ve had depression for years, it feels like most of my life. It gets better, it gets worse. But recently my grandfather passed away, and I’m not coping well with it. It’s been hard to sleep or interact. I’ve been irritable and volatile, and I feel like a lot of the people in my life are getting sick of my mood swings. I don’t feel like I have anyone, but even if I did, I’m unintentionally shoving everyone away from me. I’ve lost people in my life, which has not helped. I feel like I’m safer from a lot of hurt on my own. But everyone pulling away and me pushing them away isn’t helping, it’s only making it worse for me. I cry a lot, I’ve no interest in anything, I’ve had a lot of cutting desire (which I haven’t done in almost a year), and my suicidal tendencies have been itching at the back of my brain. I want to die; I’ve come to terms with it. But I just want it to be over with. I don’t feel like I can handle it anymore. And I don’t feel like I can talk to anyone about it cuz at the back of my mind I still tell myself it’s nothing, and I’m doing this for attention. I don’t know what to do to stop all of this, to make myself whole or fix this. Can someone please help??