my situationship doesn’t know my real age and I don’t know how to tell him

CONTEXT‼️So I downloaded a dating app I kept hearing about and I set my age as 18 not thinking anybody would really catch my eye. Mind you I’m 17. And before y’all get in the comments saying I’m in the wrong for lying about my age on an app, I KNOW, I REGRET IT NOW. Anyways I ended up matching with this guy who’s 22. I’m guessing he believed my age set in my profile because he’s never asked me how old I am. I ended up clicking with him really well, like I feel like me and him are the same person at times. We’ve been talking for almost a month now and I’m back in school now and he doesn’t know it. I’ve lowkey gotten attached to him and I’m scared if he knows the truth he’ll block me. I was planning to wait til the end of the year to tell him but I don’t want him to get more attached and then be hurt. So what do I do? How do I tell him? Literally anything will help.