advice?

so, don't get me wrong, i'm in love with my boyfriend. weve been together for 16 months.  but i'm also still in love with my ex..i haven't seen him in over a year but i still miss him. my boyfriend (b) and my ex (c) have a past and they both hate each other and i had an opportunity to choose either b or c and i chose b. it was the best decision for me, my entire family, including my dogs hated c but why do i still miss him? everyone in my family loves b but i don't know what to do anymore. why do i still love him?