ADIVCE PLEASE!!!

Hey someone help me, theres this guy I like and I'm too scared if I ask him out if he rejects me, someone please help me, or should I forget about him and move on, since he doesn't go to my school anymore but he still lives in the same town, yes I'm scared of rejection, I barely trust anyone and him I trust the most but I don't want to lose him as a friend if he rejects me. should I ask him out or not? advice please!!!! I don't know what to do, and when I see him with other girls I just get so jealous and want to slap them I'm stuck in the middle of ask out someone who might say yes, or regret not asking him out okay someone please help me.