is it alright that i want to date my ex's best friend?

[??MeGaLiCiOuS??]

i have liked him for almost three years..but we didn't talk much at the beginning of this year and i started a new job and was working with this guy who i started crushing on and things took off from there we startd talking and datin,but a month later he told me he had to move but the entire time we were dating he hid this tiny fact from me ..i broke up with him but while we dated for that month my friend that i had a hardcore crush on helped me out a lot and was there for me when ever i needed him .we have been hanging out alot lately but now he is dating this freshmen ..he told me he is not really feeling it ..and he is going to break up with her, and then the next day he and my brother and mother came up to work to see me and that night we talked and now we are going to go to prom together this year.he hasn't broke things off with his her yet. and he has told both our moms that he really likes me and he has even asked his mom if it was okay to date me so is wrong to like want him