19 and moving out soon...

Hi all, this is going to be a bit to explain...

I'm a 19 year old girl, in my sophomore year of college. I've been working nonstop since I was 16, usually 2-3 jobs at a time, and have a few thousand dollars saved up. I'm studying Business and Administrative Management; I'll be finishing my Associate's after the Fall 2018 semester (so ~1 year from now). I've been super independent and "mature for my age" my whole life, usually doing my own thing and making decisions without a whole lot of parental/familial interference. I'm currently working 3 days a week at 2 jobs, and am full-time student. I have a schedule down, no problem. But it's been frustrating to not have my own space for the last few years (sharing a room with 15 year old sister), and relations with my family have been off for a few years as well... It's time to take the next step and do my own thing.

I do have a boyfriend (we've been together 10 months- he's currently in Marine basic training though, so I'm not trying to move in with him) (naturally we're planning to get married soon-ish; after I finish school and he's got more long-term orders). At any rate, his parents have a mother-in-law apartment they've been trying to get me to rent for 2 years or so, but I had no way to get from there to work, and pretty much blew them off. Things with my parents got very rough over the summer; even though I was working 16 hour days and was literally not home long enough to cause trouble. Thus, I talked with bf's parents about the apartment; they said they'd rent it to me for $200 or $300 a month if I help around the house and such. Yay; totally doable. My mom freaked out when I mentioned it in August; reminded me of the pets I have at home right now, and the fact that I was driving Dad's truck, and said "everything is free and nice at home, you're wasting your money and causing problems if you move out." I shut up and we didn't talk for a few days, it hasn't come back up. And I never mentioned it to Dad.

I told my bf's parents that I'd rent the apartment, and I'd move in in September, or whenever I got a vehicle squared away.

Sunday (6 days ago) I -finally- bought my truck- title and everything is 100% in my name- and of course I paid for it myself. Other than winter tires and little things (an oil change, a taillight) it's good to go; I've been driving it all week. By all accounts, I should be set; throw my belongings in the truck, drive 10 miles down the road, move in, end of story.

But I haven't talked to my parents, and I REALLY don't want things to get worse between us.

I can comfortably afford to move out- pay for auto and renters insurance, rent, all utilities, all of my school costs, and groceries with a little money left each month, plus savings as an emergency & winter tire fund- and I am soooooo beyond done dealing with the noise and conflict that is a constant in my house.

Oddly enough, they've gotten nicer to me the last 3 weeks or so. Thus, the trouble is just telling them, without completely destroying our relationship. And like I said, the apartment is only ~10 miles away, so I'm still going to be seeing them often, plus some of the 5 younger siblings actually like me (lol), and will want me to come see them, so I can't just take my things and go without a word. I'll also need Dad's help with the truck fixes this first time around. Would writing a letter be weird? Should I just start packing and let them ask me what's up? Should I just drop it on them on the way to church tomorrow? I feel like I should sell them on the idea, but I know legally I don't have to, so I don't know how to proceed with the conversation...

Ugh, any advice would be greatly appreciated, I want to move out ASAP, and just get on with it.