Are your parents safe or are his parents safe? Having your parents escalate this up the ladder to the superintendent may net more effective results. (You and him can try reaching out to the superintendent yourselves, but having adults do it tends to be more effective because a lot of adults don't respect that kids are people who deserve to be listened to, unfortunately).
Are there any local or local-ish queer groups/orgs that you can find? Also any racial equality or black empowerment groups/orgs? Reach out to them for their support. They should have a good idea of the resources in your area or be able to help advocate for you. I'm sorry you and your boyfriend are going through this really scary situation. It's not at all okay.
1. IMO, the simplest definition is probably along the lines of "as the name implies, it's a type of relationship that is queer to the relationships we typically expect. It is a committed relationship that is not romantic, nor purely platonic, but is something else that cannot be easily described or defined. If you're confused, that's okay. You don't need to understand something to accept or respect it."
2. Queerplatonic is purposefully vague, which makes it hard for people to wrap their minds around, so the best definition may be to clarify what your queerplatonic relationship is rather than what anyone's could be, since a qpr can be anything people want. I don't know what that means for you. "We're friends who prioritize each other./We're friends who would rather commit to each other than to romantic partners./We're each other's most important people./We're like Meredith and Christina in Grey's Anatomy./We're very sensual and touchy but we're ultimately not romantic or sexual./We've transcended best friendshipness./We're not dating but we do check in with each other before making any big decisions./We're two people who care for each other very greatly and want to be in each other's lives but don't want to date each other." Whatever it is, don't worry about explaining what it can be. Just explain what it is to you.
3. Unfortunately, most likely, there is simply nothing you can do to force people to understand what you and your qpp have. Often, people don't understand not because you're not explaining it clearly enough but because they do not have an open mind and do not actually care to learn, which would require listening. They have set their mind, and they would prefer to keep annoying and poking at you and your qpp rather than learn and let it go and respect you and your qpp.
On one hand, I do believe this will get slightly better as you get a little older. In my personal experience, teens can be especially stubborn and mean about this kind of thing. They're learning these lessons from adults, they're trying to gain their own autonomous power, and this can tend to come out in a way that is just meanness and disrespect for other people, especially other people who are different. It can feel - and be - that adults treat you like you know nothing and are therefore undeserving of being heard, and teens can turn around and perpetrate this amongst their peers by pretending they know everything. Some people will grow out of this a bit as they age (I did!). As you get older and have more experiences, you realize how narrow your worldview is and that you don't actually know everything and can be more open to learning and growing. (Some people, anyway. Others certainly stay closed off and close-minded as a result.)
But mainly, this may just get better as you get older because you will gain more power and autonomy to walk away from people like this and keep them out of your life. You have more room to take space from people like this. You believe in yourself more and have a bit more room to stand up for yourself without being told off by the nearest teacher. You will be less stuck with dealing with people like this for 8 hours a day because even when you have to work with them, bosses will truly care more about the work and people like this will genuinely just have less time to sit around mocking you.
So the best way to deal with this is probably to give up trying to explain it and instead stop engaging in it.
"Haha, what a simp." ~ "Yep, exactly. Now, the lunch line has moved and if you don't, I shall move up in front of you."
"So you're dating then." ~ "No, but as we're not friends, I don't really care what you're determined to think about this. What did you get for question 4?"
"MaxIsCosmic and [QPP] sitting in a tree!" ~ "That does sound fun. [QPP], why don't we go find a tree to sit in? *walks away*"
"You're totally [datemates]!" ~ "Whatever you say. Oh, I better to get art. The bell is about to ring."
Flippantly accept or brush off what they're saying, then change the subject, walk away, put earbuds in, read a book, whatever. The truth is that it's unlikely you can foster an actual discussion on this because you are interested in discussing - they are merely interested in forcing their perspective on you. You cannot have a conversation if all parties aren't willing to listen, and it seems these people have proven they're not willing to listen. Disengage and focus on people you enjoy being with and engaging with. It's annoying and it's disrespectful, and they absolutely shouldn't talk over you like this. But at the end of the day, what matters is that you and your qpp are happy with your relationship. You don't need the approval or acceptance of these people. They're going to think what they're going to think, so spend your time with people who do respect you. Spend your time doing what you enjoy.
hemogoblin's post in Help (TW slurs) was marked as the answer