I reaaaally really like a guy and he's about 12 years older and i dont know what to do... Is it impossible? I mean like the age gap is too big

Are you very young? Because you kinda sound like you are. Personally I think that you have to know a lot about yourself and be independent before going into a relationship with an age gap like that. If you’re, say, 16 or 18, your personality and self esteem and self worth are all still developing and a man older than you by so much, who’s already developed those things, could very easily manipulate you into becoming who he wants you to be.