Is it normal to fantasize about a guy who i have never even talked to?

So I have been through a breakup , not recently but it wasnt easy . As a matter of fact someone on is it normal suggested me to look around and have crushes.
There is this guy in my biology class very adorable or making it brief he is totally opposite to what my ex was , shy , not player , focuses on his studies , not swept away or way too much into normal high school stuff.
I have never talked to him out of fear of rejection but he makes me forget the world he makes me forget my past relationship I actually dy dream about him , fantasize having sex with him and whenever he sits right next to me I cant help myself and keep rotating my neck to left so that I can stare his doll face ( he is beautiful not girly ) while he jot write down whatever the teacher is dictating.
I dont even have him yet and I am scared to lose him .whenever he doesnt come to the class I get so pissed and down . I literally feel like shouting at him as if he is mine or he ll care . I just love him , I just want a hug from him his arms around me I want to be protected and I want him to be that protector so that next time when my ex comes back and brag about how he fooled me and made me suck his dick and all those disgusting stuff that he mentions to torture me , he ll tell him to get lost and not dare to hurt me again .
I dont know I am so associated with him I really dont know where am I going . I dont even know how he feels about me.