Should i act upset so he notices that....?

No.... don't act upset because he will take it wrong as in you don't like him.. I always say> communication is the key to everything. I too was shy like you in school it sucks to be shy so i understand you very well. Ok since you know he liked you, what you need to do is this.... If your too shy to go to him and tell him you like him you can either have someone tell him like he did for you, or if you know his phone number you could text him. Talking by writing takes away the shyness and you'll beable to tell him anything. Just be honest with him and let him know how you feel just like you told us how you feel. Trust me if he still has feelings for you he will drop this other girl and run to you. If he likes her more he will still have respect for you for letting him know and they will def break up one day because its very rare to have a realtionship at 14 and make it to marriage. lol Best time to find a mate for life is in your 20's when guys are looking to settle down and not looking for a one night stand. Guys will say anything if they want to just sleep with you so beware of that and always let them know you'll wait till marriage because if they leave you for that reason their not going to be worth your time. Always go for the best don't go for less. You deserve someone special who will be there for you for life. Good luck with your crush.