Gets worse and worse….

Hi
This is my 3rd time posting on this website, i guess it’s because i have no one else. I am getting more and more depressed every day and don’t no what to do.I was thinking of taking an overdose when i looked up consequences of an overdose and it said brain damage and that put me off that idea.
I have being depressed for nearly two years now and i guess things are getting worse and worse lately. i think it was my friends that kept me on the right path, but now i’m no longer friends with them. i suppose i have a few friends not good friends though but i have no one i can tell this too.
Recently had a fight with my best friend because i was feeling down, she snapped at me and i over reacted by not talking to her, then i did’nt no what to say to her so i texted her and said sorry but she didnt wanna be friends anymore saying she didnt care, I think she used that as an excuse to get away from me though. While i aws texting her so got quite harsh so i did back too. The next two weeks i felt like i hated her,.. now i dunno but i still am really pissed.We werent as good friends lately anyway. well shes not the reason i’m depressed anyway sorry for rambling on.. I feel like i;m going crazy so i felt i had to get this off my chest..
Theres only one reason i’m alive and thats because of my mother i love her and dont wanna hurt her by killing myself as she has gone through alot in her life, lost both her parents from cancer in her teens and that has made her an emotional person… I’m so sad and never will be happy… ever, I dont wanna be selfish by killing myself but i feel like my heart is slowing rotting away.. I also have a lot of spare time on my hands so suicide just rushes through my head constantly. Im also an embaresment at school as i blush at every little thing and everyone notices it and thinks im weird.
Thank you for reading this,
Darren