I need help

So my boyfriend and I have been together for almost a year. Everything was amazing , fun and just like that’s the guy I love. But then after around 5-6 months he started to act very overprotective and like he didn’t trust me. He would tell me that I can’t wear certain clothes like a dress , tang tops , crop tops not none of that. So stopped and then he would tell me that he gets jealous when I would simply talk to my guy friends so I stopped doing that. Then a month ago i was texting my cousin and we have a weird relationship my cousin and I so I told him “I’m trynna fuck” but I was talking about my boyfriend and my cousin knew that cause that wasn’t the first time I’ve played around like and my cousin does the same thing my cousin and I are both in a relationship and it’s completely disgusting to date or have sexual interest in your cousin 🤮 I understand that he didn’t know that he was my cousin but I told him and even when I told him he said “I was expecting you to cheat on me and why don’t you just break up with me already” he said a lot more and he was full on cursing at me and now he made me block my own cousin because my boyfriend would not stop talking about him so I blocked my own cousin. My boyfriend doesn’t trust my own family. Also he is always saying stuff like my family are raising me stupid and that my parents are stupid , he only says all of that cause they don’t like him cause of the way they found out about us and it bothers me cause that’s my family even if we aren’t able to see each other there’s no reason to talk about my family. Also he doesnt let me text my guy friends but he is allowed to call and text his which is dumb but at this point I don’t care I am talking to my guy friends again. Also I don’t know if I should or not break up with him because he has very bad thinking like he wants to die and this stuff and I try to be there for him always but it’s hard really hard and also I am so young I’m 15 and his 18 I really want to enjoy my high school years but I really love him and don’t want to leave him all alone especially with the way he thinks. Idk I just need help please on what to do or say to him.