That pretty much describes the last >3 years of my life. More than 3 years wasted because of denial. Then, from December 2009 to April 2010, it all spiralled down to a point where I was so exhausted, indifferent and in (psychological) pain that I decided to commit suicide.

Long short story, I almost committed suicide, but ended up not doing it. I've been diagnosed with major depressive disorder, and I'm currently taking antidepressants.

Here are a few tips for people who are depressive, especially those who feel suicidal.
I learned that from experience:

• Suicide hotlines are complete bullshit. Seriously. Most people working there are volunteers that are unfortunately not qualified enough to deal with those sort of situations. Every time I've called a suicide hotline (I've called several different ones), I've been either infantilized or not taken seriously. If ever you feel like committing suicide immediately, don't call a suicide hotline.
• Instead of calling a suicide hotline, if you are serious about killing yourself, dial 9-1-1 or go to the nearest emergency room. Once at the hospital, tell them you'll kill yourself if you don't get help immediately.
• If you are serious about killing yourself, but not immediately, try calling a close friend if you have one. Yes, it's going to be awkward, but that person would prefer to know you're about to cut your wrists rather than spending the next few years wondering every day why you didn't speak to him/her. Seriously. In every "worst decision"/"biggest regret" thread on Reddit, there are many people who, decades later, still blame themselves for the death of a loved one.
• Free healthcare is great, but it also means you sometimes have to wait months before getting access to some medical services. For example, if you want to consult a psychologist in a community health centre, you will be put on a waiting list. They will ask you questions to assess the priority of your case. To avoid being put on a waiting list for weeks, if you feel like you can't wait that long, lie to the person who asks you questions. One of the first questions you will be asked is "Have you tried committing suicide before?". Always answer "yes", even if that's a lie. If you answer "no", for some stupid reason, they will handle your case like it's not urgent. It doesn't matter even if you're going to commit suicide within 24 hours: if you've never tried to kill yourself before, you'll never get to see a psychologist in time. It took me weeks to figure out why I was always disqualified to consult a psychologist immediately. That's the reason.
• Being depressed or suicidal puts you in a kafkaesque situation. A lot of people do not have the energy to deal with this bureaucratic nightmare and end up killing themselves. Even if that's the 20th phone call you've made in attempt to get help, and it still doesn't work, do not despair! Like I've said before, if nothing works because nobody believes you're serious about killing yourself, dial 9-1-1 or go to the ER. Avoid clinics without appointment, because doctors there usually do not prescribe psychotropes (such as antidepressants) if you're not one of their patients. Thankfully, depression qualifies you for getting a family doctor even if you otherwise wouldn't qualify. Take an appointment at a clinic where they still take patients, ask a doctor to become your family physician, and when he asks you if you suffer from a chronic disease, answer "depression". That way, he can become your family doctor, and since you are his patient, he will be able to prescribe you antidepressants.
• People are fucking idiots. Most of them. They will tell you to "get over it". They will say "suicide is not a solution". They will tell you you have no reason to complain. They will say you're just whiny, and that there are people in Africa who have tougher lives than you. You'll hear this every day. Seriously, that is utter fucking bullshit. Depression is a mental illness, not a life choice. Most times, you can't just "get over it". But it can be cured. Those people who don't know shit about depression will lead you to believe you deserve to feel shitty. Unless there is a physiological cause for your depression, then it's true that you may have to change your lifestylke in order to get your life back on tracks. However, it's not as simple as "not whining". Being depressed, you won't have the motivation or energy to get your life back on tracks, and that is understandable. Begin by taking medication that will help you regain some of the energy and motivation you once had, and then you will be able to work on changing what you don't like in your life.
• About "suicide is not a solution": it is simply not true. However, there is always another solution: the veil of depression makes you blind and you are just not able to see that solution. Suicide becomes a tempting solution when the (psychological) pain is greater than the positive aspects of life. Committing suicide is very hard, because there is always some sort of instinctive life force in you that tries to keep you from killing yourself. Try to channel on that inner force of life. That last tidbit of energy that keeps pushing you harder and harder, even when it seems you are no longer able to stay alive. Hopefully, it'll allow you to think twice before choosing a permanent solution for a temporary problem.
• You're taking an antidepressant (typically a SSRI) and you have negative sexual side effects, such as erectile dysfunction or inability to reach orgasm? Talk to your doctor about Wellbutrin. It's an antidepressant that does not cause sexual dysfunction. Be aware, however, that not all types of antidepressants work on everybody, and that switching antidepressants also poses the risk of bringing back suicidal thoughts temporarily, until the new drug starts to work.