Thanks JessF,
The main reason why I avoided discussing my issues and seeking help was because I didn't want to burden my friends or family. I kept telling them, and myself, that I could deal with it on my own. Obviously I couldn't.
What advice would I give my friends? Well, for a long time I was very angry at them. What kind of a friend would abandon me in such a fragile state? I blamed them and victimised myself. It took a while for me to forgive them and accept my own faults. I suppose the best piece of advice I could give is to just be there. When I think about how I felt at my very lowest point, when all I could think about was suicide, I remember feeling extremely lonely. I remember finding any excuse to text someone and staring at my phone wishing they would call. It really is amazing much a "Hey, how was your day today?" or a "Hey, we should catch up for coffee soon!" can change someone's day and even their mindset. So just be there. Be present, be persistent and be patient. And remind them in even the most subtle ways that you are thinking of them and that you love them.
As far as giving myself advice goes, I would have to remind myself the same thing. These are the people who love me, care for me and want to support me. Opening up and allowing myself to be vulnerable won't hurt them, but closing myself off and allowing my issues to pile up just might. I know I would support them through anything, so why couldn't I let them do the same for me? We're all human and at some point or another, we're going to need to lean on someone else. Sometimes you just need to let yourself be weak and vulnerable before you can heal.