Is it normal that im horny all the time....

im horny all the time but the only problem is that im only attracted to girls. ive been with a guy but that was 3 years ago. i mean like every time i think about other girls i feel sick to my stomach because i need sex so bad. my last girlfreind would have sex with me all day every day but i think she got tired of it and broke up with me. i dont know what to do im always horny and its messing with my mind. is this normal and what should i do.