Give up. Kill who you are in your mind this moment and rebirth into the next moment a fresh, spry, rejuvenated 18-year old. You have the world at your fingertips, yet you are choosing to live unconsciously. Wake up from your coma, accept the truth of what is, and make the next right decision that will benefit you now and lead to contentedness in the future.
If you want to self-loathe over your girlfriend by destroying your mind and body, you can. If you want to get up, knock the dust off your jeans, and keep going, you can. This life is all about what you choose to do with it and what you want to become. I am not talking about becoming a rock star or a movie-stunt driver or a businessman: I am talking about becoming a victim to your suffering or rising above the ashes and allowing the suffering to become one with you. To know the good we must know the bad. However, we cannot stay there, for that is when self-loathing and wanting to kill our "selves" --separate from our body and soul-- starts to delude our existence. The same is for the good: we cannot stay. As with all things, each moment brings what it brings. We must embrace it and move on.
Let your old self die, my friend. Do not label yourself anything except a man that suffers. We all suffer in this life. I self-loathed and played victim for years while abusing drugs and alcohol. On top of it, I was in a six-year relationship that sucked the life out of me and broke me down mentally, physically, emotionally, and spiritually. Today, it feels like a lifetime ago and that is because with the death of my old self and the life I had comes the birth of my new self and a brand new life.
I do not know who the "I" is hating "myself", but I relate completely. The fact is, we are all perfect. I was supposed to be exactly how I am, and I am just as I am. I should never compare myself to others or feel inadequate. I do, but I have to remind myself that I am unique and a vessel to explore this world. I have to love myself. I have to trust myself, embrace myself, smile at myself, laugh at myself. I don't have to, but I want to. I am the only one I have in this world. I come into this world alone and I will exit alone. Trust and love yourself more than anybody else.
I do not know what you need to do, but I will tell you there are no solutions in intoxicants. You have every right to use if you want to. However, know that in the end, you will break your body and mind. When you set your mind aflame, it is hard to gather enough water to put it out.
Life is suffering and we must transcend it. What your path is, I do not know. You start by making the next right decision for yourself. I also do not know what this is for you, but I am guessing it's the choice that will make you feel complete and add to a whole for the future. You are young and have life experiences that many people will not come into contact with. This is your offering as wisdom to yourself and to others as being wise, if you allow the experiences to be what they were. We all have wisdom, but until we choose to use it for good and to stop repeating past mishaps, we are not wise.
Realize all things are transitory, nothing stays the same. Maybe you have had your time with that girl and heroin and your paths are no longer crossing. Realize the gravity of the life you hold by just existing. Realize you can do anything you can dream. If you want to gain 20 pounds of muscle, you can. If you want to get a job and save $10,000 in a year, you can. If you want to take a spiritual trip to India, you can. If you want to stargaze all night and sleep on the tips of mother nature's fingers all day, you can. Where there is a will there is a way. Where there is life there is possibility. You are only snuffing this beautiful life out if you choose drugs.
You know what you need to do. You will be OK.