Some kf my advice is going to sound weird, so please take what is useful and leave behind what you can't bring yourself to do.
First and foremost, seek treatment for your depression. Whether it is therapy, medication (I had a good experience with Prozac), or meditation (a technique called mindfulness). All three can help you.
Second, you are not "hard hearted." Unrequited love isvery diffi ult to deal with. You will do better if you understand that the feelings you had were not really "love " They were infatuation. Love happens when someone loves you back.
Also, it's clesr that you are using drugs to self-medicate. I know people who smoke weed because it helps them relax. When you need it to deal with difficult problems, well...your problems will still be there when the weed wears off. So maybe take a break, get your life in order, and only do it when you are happy. Same with dipping. The nicotene probavly helps you deal with anxiety. Prozac can do this as well, and it doesn't cause cancer (note: it is loathed on Reddit, but it's not the only anti-depressant out there--talk to your doctor about its possibke application and side-effects.)
OK, you were probably wondering what the weird part was...here goes: why not ask your girlfriend to show you her vagina. You seem to be incredibly shy, to the point that it's hindering your development with the opposite sex. I'm guessing that your girlfriend (that's what she is) wants you to take her pants off. It's extemely hard for young women to send that message, lest they be taken for a flawed human being...so expressing the simple sexual curiosity of "hey, I've never seen one in person" (again, a guess, but I'd bet money on it) could be a way of giving you something intimate to share that relieves what must be a ton of curiosity and just plain horniness. If she gets offended by the suggestion, feel free to blame me. Not all of my advice is good advice, after all. But, if you do and she accepts, I'd double down that the next thing that happens will be magical (even if it's just her pulling her pants up and you now suddenly having the courage to give her a hug and kiss). Good luck, young man. You won't be young forever, but you are (almost certainly) be a man for the rest of your life. Here's to hoping you enjoy the parts of you that make you a man, instead of suffering for them.