is it love????? (this sounds like a BL manga)

ok, ima be honesty wit you. like im not kidding, but i just need help rn.

So I'm currently 18 and 3 years ago my dad met this woman, her name's Veronica. They got married and now I officially have a new step-mom. Little did I know, she brought the Devil incarnate with her. Her son, now my step-brother, is this tall attractive dude who I've envied ever since. I don't hate him, but he stole my crush. cough cough. Now I'm fairly tall, 5'10 but that's not enough to compare to him. My dad claims he loves us equally, but sometimes I get jealous. sigh. Anyway, 2 months ago, he told me likes me. "What. ME?" "Yeah, you. I've liked you for 3 years. You don't know have to tell me your answer now." I seriously don't know what to do, I'm not even kidding as well. I don't know what I did to make him like me. I'm not like homophobic, but it's been uncomfortable. I don't know what to do. And recently, I just feel nervous and shy around him. Like a fucking girl who sees her crush passing by (no offense ladies, it's okay to do that). I keep thinking of him. I don't want to admit since people might think it's weird. But it's the 21st century, we have internet so I'll just use this for answers. Maybe I should see a therapist, whatever I don't know. By the way, I'm guy.