I need some advice girls

Alright, so where do I begin. I have been dating my boyfriend for nearly a year. We have been through way more than most relationships these days, I’m 15 and he’s almost 16. We are kids in an adult relationship. We have dealt with family issues, jealousy issues, people issues, everything. Family was a big one for us, though. So basically, his mother has 7 kids. She threw 4 of them out because she didn’t like them, and made the other 3’s lives hell (my boyfriend included). He got the worst of it, though. It doesn’t help that his sister is dating her step brother, and his mom expected him to like his step sister. So when he started dating me, she got mad, instantly didn’t like me. That’s a great one, huh. She was terrible to me and him, and our relationship. But we stayed strong, because he was moving out of there. And once he was out, the bad would go away. He was worth all of the pain and hurt. His mom constantly called me fat, stupid, a bitch, and his sister added on. She’s 17, yet she acts 3 just like her mom. They were hard on my boyfriend, very hard. It hurt me so much to go through that, and to also have to watch him go through it. Eventually, I bubble wrapped myself and put up walls to protect myself from all of that toxic stuff that they were throwing at me. Then, he moved in with his nana, and we could finally breath. Our relationship has been doing very very good. But now, since he’s been moved out for 2 months (he’s gone back there to see how they are and stuff because he misses them, they’re still his family after all), now he wants to go back to spend the night. We have exams starting tomorrow, and tomorrow night he’s coming over to my house to stay the night to study for the french exam we have together the next day (Wednesday). But on Wednesday night, he’s going over to stay the night there. I don’t agree with it, obviously. I’m terrified. She might not let him go to school (for no reason, she did it all the time when he lived there). But also, I’m terrified because I know he’s going to get his heart broken again by them. This always happens. He believes they have changed, then they bite him in the ass. He is a very forgiving person, which is one of the reasons why I love him. But this, it’s scary. I have taken off my bubble wrap I had to protect myself. I have let all of my walls down. And if they start what they did before again, I have no resources to protect myself from it. I can’t take that again. He is the love of my life, and I know what you’re going to say. That “I’m too young to know what love is”. But this is it. This is really it. He is the love of my life. We are going to grow old together, go on trips , but a house, have fights about mortgages, have kids. This is it. He is it. He is everything to me. Don’t I have a right to be scared? To be confused in a sense where he is going back to the people who made our lives hell for 8 months? To the people who made it so hard on us to be in a relationship. I am terrified. Please give me advice.