Brady, I have absolutely NO experience in leaving loved family members the way you are doing, but I have a LOT of experience with fear. And I can tell you that in my experience, I've seen pretty much two choices: I could control my fear just enough so that I could do the things I wanted to do and was afraid to do, or I could let the fear control and dominate me.
Going with the first choice is scary as hell, but the second choice is so much worse because when I chickened out--and that's how I saw it--I felt no self-respect for myself and started obsessing over the thing that I was afraid to do. It's as if all of the brave and gutsy things I had done in the past meant nothing. I hate feeling that way. As for the first choice, the fear actually does not last long, and you maintain your self-respect and get so many other good things out of it.
If you do the gutsy thing, you can always stay in touch with loved ones and see them when you're able. You'll have a shot at the job, you'll be able to live with your boyfriend, and you'll be off on a terrific adventure. And you know what? Your parents will hurt some, but you are an adult now. Your moving away was pretty much inevitable. They know this, and you know this.
Your boyfriend can't be with you while you take this step, right? Well, pretend that he is. If you're driving off to school or whatever, pretend that he's right there in the passenger seat, rooting you on, making jokes, telling you how wonderful and brave and sexy you are.
The last day, when you're saying good-bye, is THE HARDEST. I know this from the experiences of some of my friends. And the first couple of days in a new situation are also hard. Once you get past them, you'll be able to move forward.
The fear will peak, and then it will start to dissipate, and then you'll start enjoying yourself. Trust me on this.
My partner has a great bit of wisdom that I rely on whether I'm preparing for qualifying exams or getting lost after taking the wrong offramp. When I think of him saying it in his gentle, reasonable voice, it brings a smile to my face and dispels some of the tension.
"Think of it as an adventure."