First things first, I’d suggest looking into Big Brothers, Big Sisters if you’re in America. I’ve been a part of their program and it’s a great organization dedicated to helping kids exactly like this
OK, onto real advice: it sounds like you’re a woman and one of the things you need to address early with young men is respect. He will become significantly stronger than you very soon. He will have a ton of hormones pumping through his body. He is going to become dangerous to himself and others. He will be curious about how strong he is. You have to make sure he explores that safety. This is something all men go through and it’s important to have a good foundation or he can start spiraling down bad paths. You need to police his internet usage, his friends, and his role models or he could very easily start sliding into anti-women and abusive views
If he’s not enrolled in any sort of physical activity I would encourage you to find one. He’s going to have basically unlimited energy and channeling that into sports is usually better than the alternatives. That’s also tricky because you need to pay attention to the leadership of those activities to ensure that they are good influences
Now the fun stuff: he is going to be hungry for the next 5 years. If you haven’t grown up with boys it’s hard to understand but he can eat 6000 calories in a day and barely notice. My family used to order 2 pizzas when I was a teen, I would eat an entire one and they would eat the other. I’m not exaggerating when I say my average food in a day was a full continental breakfast, 2 deli sandwiches, chips, a dessert and a soda for lunch, an after school snack (usually leftovers), a large dinner, and dessert. I’m not a fat guy, nor was I in school. You will likely think at some point “he can’t possibly be eating that much food” and I assure you that he can
Ultimately what is important is that you have to build a good moral foundation for him. You will lose the ability to control him and when that happens all of the work you’ve done raising him will reflect in the way he acts
Unfortunately, yeah. The more you let people walk over you the more comfortable they get doing it. Being blunt is a good way to stop that kind of behavior, when someone is rude asking direct questions like “why are you saying that about them?” makes people uncomfortable and will get them to stop dragging you into drama. Especially in today’s American climate people feel emboldened to attack people they see as “weak” so you need to not appear “weak” and (this is the much more difficult part) stand up for everyone else who the bullies are targeting