Rucifer, I hope I can give you some encouragement, as it is probably not as black as it seems.
From a purely practical standpoint, the smaller the company you go to, the less likely there is to be a background check. I don't know what line of work you are looking to go into, or what you intend to study, but this general rule holds true across many industries. Obviously you would probably not go knocking at Homeland Security, and there will be other doors that are closed, but don't let that cloud your ability to find the doors that are open - of which I promise there are many.
Also from a practical standpoint realize that after a period of time your employment history becomes who you are, the older something is the less it matters. Getting the first job is tough for all of us, but you build from there.
What I am saying is not mere theory, it is my experience. I took a contract position 2 years ago, and in January I came on as an employee. Since this is the internet and I use my real name I'm going to keep this vague, but let's just say I had to tell them about something in my background that I was not proud of. Like your case it was not murder or anything horrible, but a definite black mark on what I felt was otherwise a good record. The person running the check said, "because you told me (instead of my finding it out), and it was quite awhile ago, I cannot see how it can possibly be a problem." And it wasn't.
A good friend of mine (who benches over 400#! (and who cannot believe I now lift)) was discharged honorably and became a Physical Therapist. During that career he made some serious missteps (not on the job), worse than what you mention, and lost his license as a PT which he can never get back. That was a long time ago and he's been gainfully employed ever since he got his head out of the blackness that had led to the mistakes. He cannot be a PT, but he still helps people, he always has and he always will. He's a great guy and he brings cheer everywhere he goes.
To wrap up on a mushy note, my friend the PT is a *mild* case of some of the life turnarounds I've seen. The world can be cold and some realities cannot be erased, but mercy is abundant in this life, and second chances abound, third chances, and many more. I've gotten more than one myself. I'm sure others will say the same. Take heart, keep up your studies, and just worry about finding that one company that will hire the man in front of them instead of what they see on paper from x years ago. I promise they are out there.