I really need some advice

ms.
As I have stated previously, I have been dating my boyfriend for 4 years (he is my first love). We have not had sex and we have decided to wait until we are married, (we're both virgins). We kiss and do pretty much everything else. I have noticed almost a year now that he stopped being into the intimate things we use to do. He doesn't even feel like kissing me that much. I've noticed and asked and he just ignores me. Well recently I finally had enough and confronted him and asked him why he is never in the mood for anything. I would literally go down on him and he wouldn't be into it. He finally told me that he is addicted to masturbation and he does it so much that he wears himself out. And that he loves me very much but it has affected his sexual drive towards me. I feel so heartbroken and feel like I've been left in the dark. He says that he loves me very much and that it will change once we get married because then we will actually have sex. But what if it doesn't change anything ? What if he always just wants to take care of himself. (He doesn't want me anywhere near him when he does it and and has hid it from me for 4 years). When I'm horny he can't even have phone sex with me because he's never in the mood for me but he masturbated more than 10x a day. He says he feels digusted with himself and he's trying to stop. I am so worried that when we get married he will neglect me sexually. I can't see myself with anyone else. I love him dearly. Am I overreacting? As anyone had a similar experience before? I am so hurt and lost.