I think my boyfriend is being abused by his parents need some advice/Guidance...?

[kristen]

My boyfriend is 16 and as am i we have been together for two years. Well i think his parents are abusing him he never wants to go home and he sleeps over at friends or my house whenever he can. And well today i walked in on him as he was changing his t-shirt and noticed a lot of deep cuts on his back and on his abs. When he saw me he just cried so i went up and just hugged him and told him how much i loved him and how i still think his body is so hot and beautiful to me. Well my parents let him sleep over tonight since we go to the same school and they love him and everything and he sleeps in our guest bedroom and he respects there rules. Well when i asked him what they were from he wouldn't tell me. And i am super worried about him and i can't sleep and i want to tell my parents but i don't want to do betray his trust super unsure of what to do. Advice? I really need some guidance here.