Thirty-One is barely an adult. You haven't really missed out. You just had a different set of experiences than non-addicts. Your experiences were profound as are all addicts' experiences. A person whose never been an addict isn't guaranteed positive experiences. You could have done worse for yourself not using drugs as a crutch, and you may have had to feel your pain in excruciating detail without relief which could have caused worse outcomes than addiction. It's not accurate to look at X persons' lives without drugs and compare it yours with or without drugs.
But I think what you perceived to have been missing out, you actually won't miss out in the big picture, the really big picture. I am an atheist and a science minded person. The math of quantum mechanics strongly suggest that we live in an eternal multiverse. You can think of a universe as an evolving set of patterns, some patterns are stars, some are moons or gaseous nebula, or a blade of grass, every object consists of patterns and none more so patternlike than life. Your whole body and mind are a DNA protein fractal with a specific pattern. Your consciousness is a very small part of the overall pattern that is your human form. So, your ability to feel awake and aware that you exist is drawn from a small but very significant sub pattern inside your brain. Here is where it gets weird but bear with me if I'm not too boring.
When you die you lose consciousness and your "clock", your perception of time, stops. This means that even though you eventually die, given enough time and space in a multiverse, your exact same pattern of consciousness will emerge over and over. It's a matter and function of odds. Since you can't feel the time between your passing in this verse and popping into existence in some future universe, it's like your memory was wiped and you were instantly transported to new universe.
A good example of this idea was the holographic doctor on Star Trek Voyager whose holomatrix was taken off line 800 years prior and was turned on again. According to the doctor, no time had passed. It wouldn't have mattered if the doctor had waited infinite years before being turned on again, it would have felt instantaneous. That holographic pattern is similar to the pattern of consciousness. It seems inevitable that the moment you die the very next moment you are tansported across the multiverse. Even wierder, there are probably multiple copies of you living a variety of lives if the multiverse is big enough in terms of space.
This life is your current screen. You were always going to be an addict in this life. Relativity strongly suggests that reality is all cause and effect. Free will is an illusion. This means we don't have a choice but rather we are like characters of a book whose story has been written but we feel it's new and unfolding before our eyes. A character in a book has the illusion of choice and we read each page with anticipation that he'll make the right choice and save the planet. But the entire story has already been written, right up to The End.
The trick for you is, what's next? You probably have loved ones who prefer you die of old age years from now, people who may rely on you for things you can't even concieve of. You can feel some sense of security knowing that you never really die, that you will enter a new phase of existence, a new screen, eventually trying out every iteration of being that can contain the sub pattern of your consciousness, but there may be connections here and now worth keeping.
The next screen you embark to will have your same consciousness but in all likelihood won't be even remotely human nor will you have any memories. You might be amphibioid in some planet in some universe that has an extra fundamental force that our universe doesn't have. On this screen you are a human who had or has an affinity for drug use. You never had a choice. None of us do.
There is no judgment in the cosmos. Judgment is a simian simulation that came about as part of our evolution into becoming Great Apes. At your death, all of your biases and prejudices will disappear and you will end up with entirely new ones as a member of a different species. This is not your personality surviving, it's your ability to feel awake which is surviving. Ever wish you were someone else? You were everything else before your consciousness appeared in this verse and you will be again after.
It sounds like you have some things and people worth holding onto, some new experiences to check out while in this form. Remember that in this scenario the next screen might not be as good as this one. It could be worse or could be better but statistically, it will probably about the same.
If you find the prospect of being a sentient bat-creature with tentacles for feet or some indescribable being too different to contemplate then maybe this life is still for you.
You can alleviate pain locally but you can't escape existence. If you are scared suicide would destroy your family and fiends then it's likely going to be at a minimum very hurtful for them and you may have to calculate their feelings into the overall equation. Its promising for your crew to iteration of you that you are able to consider your family's and friend's pain objectively that you aren't lying to yourself that nobody cares. Truth is one of the most precious of things.
You are changing contantly and the nature of your addiction will also change, probably become less overall as you get older. Old folks just don't have that desire for massive adventure that youth has. You have already changed from the person you were back in the deepest throes of your addiction. Killing that person is impossible. He's already gone! So consider things carefully and objectively as you can and whatever your decision I hope it provides you with the relief and meaning you desire.