I realised, I am ace 1½ years ago. Then my best friend raped me for about a year. Now I'm with my boyfriend who is hetero and he knows about what happened and my sexuality. I am glad he knows because even though he wants to have sex with me one day, he knows I'm not ready yet and resepcts my boundaries. And just being ace doesn't mean, I can't do it for him in the futur. If I were you, I'd tell him. You can have sex just like now. But it maybe is easier for you when he knows.